全文获取类型
收费全文 | 7349篇 |
免费 | 353篇 |
国内免费 | 185篇 |
专业分类
耳鼻咽喉 | 10篇 |
儿科学 | 260篇 |
妇产科学 | 177篇 |
基础医学 | 324篇 |
口腔科学 | 25篇 |
临床医学 | 1086篇 |
内科学 | 774篇 |
皮肤病学 | 33篇 |
神经病学 | 136篇 |
特种医学 | 454篇 |
外科学 | 2257篇 |
综合类 | 1014篇 |
预防医学 | 404篇 |
眼科学 | 11篇 |
药学 | 489篇 |
8篇 | |
中国医学 | 296篇 |
肿瘤学 | 129篇 |
出版年
2024年 | 15篇 |
2023年 | 124篇 |
2022年 | 235篇 |
2021年 | 275篇 |
2020年 | 227篇 |
2019年 | 236篇 |
2018年 | 220篇 |
2017年 | 182篇 |
2016年 | 198篇 |
2015年 | 230篇 |
2014年 | 568篇 |
2013年 | 548篇 |
2012年 | 464篇 |
2011年 | 561篇 |
2010年 | 436篇 |
2009年 | 415篇 |
2008年 | 434篇 |
2007年 | 356篇 |
2006年 | 311篇 |
2005年 | 251篇 |
2004年 | 230篇 |
2003年 | 187篇 |
2002年 | 143篇 |
2001年 | 131篇 |
2000年 | 100篇 |
1999年 | 90篇 |
1998年 | 71篇 |
1997年 | 70篇 |
1996年 | 52篇 |
1995年 | 39篇 |
1994年 | 45篇 |
1993年 | 39篇 |
1992年 | 40篇 |
1991年 | 42篇 |
1990年 | 32篇 |
1989年 | 36篇 |
1988年 | 25篇 |
1987年 | 29篇 |
1986年 | 18篇 |
1985年 | 39篇 |
1984年 | 21篇 |
1983年 | 12篇 |
1982年 | 21篇 |
1981年 | 14篇 |
1980年 | 19篇 |
1979年 | 13篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 10篇 |
1975年 | 5篇 |
排序方式: 共有7887条查询结果,搜索用时 31 毫秒
51.
Yuta Ishizuka Yasushi Ishida Qing-Hua Jin Ayumi Shimokawa Mitsuhiko Saita Kazuo Kato Takato Kunitake Takamitsu Hanamori Yoshio Mitsuyama Hiroshi Kannan 《Brain research》1998,789(1):10
Nitric oxide (NO) has recently been shown to modulate the hypothalamic–pituitary–adrenal axis response to interleukin-1β (IL-1β). We measured levels of nitrite (NO2−) and nitrate (NO3−) in the hypothalamic paraventricular nucleus (PVN) region using an in vivo brain microdialysis technique in conscious rats. Intraperitoneally administered IL-1β produced a significant increase in both NO2− and NO3− levels in the PVN region. We also examined the possible involvement of the abdominal vagal afferent nerves in this effect. In abdominal-vagotomized rats, the increase was significantly attenuated compared to that in sham-operated rats. Our results suggest that the abdominal vagal afferent nerves are involved in intraperitoneally administered IL-1β-induced NO release in the PVN region. 相似文献
52.
Donald F. Orton M.D. Dennis F. Strauss M.D. Michael Hummel M.D. Dale Orton M.D. F.A.C.E.P. 《Emergency radiology》1998,5(3):173-175
The intraperitoneal mass most commonly encountered after blunt abdominal truama is a hematoma. However, one must also consider
unusual bulky tumors that can have imaging characteristics similar to those of hematoma. The most typical of these neoplasms
is lymphoma, but a desmoplastic small cell tumor also may be observed. The presentation and imaging findings of a desmoplastic
small tumor are described. 相似文献
53.
Heinz Schurawitzki M.D. Paul C. Hajek Josef Kramer Florian Grabenwöger Walter Klepetko Anton Moritz 《Cardiovascular and interventional radiology》1989,12(1):10-13
In a radiologic search for embolized leaflets of Edwards-Duromedics bileaflet valves in 2 patients, the embolized fragments were localized in the iliac vessels using computed tomography. Sonography was successful in one case and standard X-ray films of the abdomen were negative in both cases.In vitro investigations with Björk-Shiley and Edwards-Duromedics leaflets suggested that standard X-ray films of the abdomen and pelvis should be considered as the first investigational technique. If negative, computed tomography of the lower abdomen should be done. 相似文献
54.
Originally, allogeneic hematopoietic stem cell transplantation (HSCT) was viewed as a form of rescue from the marrow lethal
effects of high doses of chemo-radiotherapy used to both eradicate malignancy and to provide sufficient immunosuppression
to ensure allogeneic engraftment. Clear evience of a therapeutic graft-versus-tumor (GVT) effect mediated by allogeneic affector
cells (T cells) has prompted the exploration of HSCT regimens that rely solely upon host immunosuppression (non-myeloblative)
to facilitate allogenic donor engraftment. The engrafted donor effector cells are then used to accomplish the task of eradicating
host malignant cells. The non-myeloblative regimen developed in Seattle uses 2 Gy total body irradiation (TBI) before transplant
followed by postgrafting cyclosporine (CSP) and mycophenolate mofetil (MMF). This regimen resulted in initial mixed donor-host
chimerism in all patients with hematologic malignancies and genetic disorders who received HLA-matched sibling allografts.
The 17% incidence of graft rejection was reduced to 3% with the addition of fludarabine, 30 mg/m2/day on d-4,-3, and-2. The non-myeloblative combination of fludarabine/TBI has also been successful at achieving high engraftment
rates in recipients of 10 of 10 HLA antigen matched unrelated donor HSCTs in patients with hematologic malignancies. By reducing
acute toxicities relative to conventional HSCT, most patients have received their pre- and post-HSCT therapy almost exclusively
as outpatients. Acute and chronic GVHD occur after non-myeloablative HSCT, but the incidence and severity appear less compared
to conventional HSCT. As in conventional transplants, immune dysregulation from GVHD and its treatment and delayed reconstitution
of immune function continue to present risks to patients who have otherwise undergone successful non-myeloablative HSCT. Cellular
therapeutic effects have been nobserved after non-myeloblative HSCT such as correction of inherited genetic disorders, and
eradication of hematologic malignant diseases and renal cell carcinoma via GVT responses. 相似文献
55.
Matsuura-Sawada R Murakami T Ozawa Y Nabeshima H Akahira J Sato Y Koyanagi Y Ito M Terada Y Okamura K 《Human reproduction (Oxford, England)》2005,20(6):1477-1484
BACKGROUND: Cultures of human endometrial tissue are useful for analysing the mechanisms underlying the menstrual cycle. However, long-term culture of endometrial tissue is difficult in vitro. Xenotransplantation of normal human endometrial tissue into immunodeficient mice could allow prolonged survival of the transplanted tissues. METHODS: Proliferative-phase endometrial tissue samples from three women were transplanted into the subcutaneous space of ovariectomized, immunodeficient, non-obese diabetic (NOD)/severe combined immunodeficiency (SCID)/gammaC(null) (NOG) mice. The mice were treated with 17beta-estradiol (E2) for the first 14 days after transplantation, followed by E2 plus progesterone for the next 14 days. The transplants were investigated morphologically and immunohistochemically at various times after implantation. RESULTS: The transplanted tissues contained large numbers of small glands, pseudostratification of the nuclei and dense stroma after treatment with E2 alone. After treatment with E2 plus progesterone, subnuclear vacuolation, luminal secretion and decidualization of the stroma were observed. When the hormone treatment ceased, tissue destruction occurred and the transplants returned to the proliferative phase. Lymphocytes were identified immunohistochemically: the numbers of CD56-positive and CD16-negative cells increased significantly in the stroma during the late secretory phase (day 28). CONCLUSIONS: Human endometrial tissue transplanted into NOG mice showed similar histological changes to eutopic endometrial tissue during treatment with sex steroid hormones for 1 month. Moreover, lymphocytes were produced in the transplanted human endometrial tissue. This system represents a new experimental model of the human endometrium in vivo. 相似文献
56.
P. A. T. Kelly F. H. Gage M. Ingvar O. Lindvall U. Stenevi A. Björklund 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1985,58(3):570-579
Summary Transection of the septo-hippocampal connections through fimbria-fornix damage in the rat results in profound hippocampal cholinergic deafferentation, and, when applied bilaterally, leads to severe and long-lasting impairments in learning and memory. Previous studies have shown that intrahippocampal septal grafts can reestablish a new cholinergic innervation in the inititally denervated hippocampal formation and at least partly compensate for the lesion-induced learning impairments in fimbria-fornix lesioned rats. The purpose of the present study was to determine the magnitude of lesion-induced alterations in cerebral function as reflected in local glucose use measured by (14C)-2-deoxyglucose (2-DG) autoradiography, and the degree to which this index of functional activity could be normalized following reinnervation from transplants of fetal cerebral tissue from the primordial septal region. Six months after unilateral fimbriafornix transection the rate of glucose utilization was reduced markedly throughout the ipsilateral hippocampus when compared to the intact contralateral side, while in the neocortex only the cingulate cortex showed long-lasting reductions in glucose use. Rats that received a transplant of fetal septal-diagonal band tissue at the time of fimbria-fornix transection, and were sacrificed 6 months later, displayed significantly greater glucose utilization in the ipsilateral hippocampus and cingulate cortex than was measured in these areas in rats with lesion alone. The recovery in glucose use was paralleled by a significant increase in acetylcholinesterase (AChE) staining in several areas of the ipsilateral hippocampal formation and cingulate cortex. This index of graft-induced cholinergic reinnervation was, moreover, significantly correlated with the rate of glucose use. Thus, in the fimbria-fornix transected animals the magnitude of glucose depression correlated with the extent of reduction in AChE staining, and in the grafted animals the degree of normalization of glucose use was correlated with the graft-induced increase in AChE-staining density. These results thus indicate that the 2-DG autoradiographic technique can provide a unique opportunity to map both altered functional activity in localized areas of the brain following specific lesions and the extent to which transplant-derived reinnervation of the host may induce a return to normal functional levels in the target site.ETP and Royal Society (London) visiting fellow 相似文献
57.
目的:探讨人工补片无张力疝修补术的疗效和优点。方法:对59例71个腹外疝在疝囊高位结扎后行人工补片无张力修补术的临床效果进行回顾性分析。结果:本组51例63个腹股沟疝和股疝的手术时间为30—80min,平均55min。术后切口均一期愈合,无切口感染、硬结、异物反应等并发症;术后并发短暂尿潴留2例;阴囊血肿2例、积液4例5侧。腹股沟疝术后5~7天(平均6天)出院,切口疝术后8-11天(平均9天)出院。随访5—51个月,复发2例。结论:人工补片无张力疝修补术是一种简单、安全、痛苦小、恢复快、效果好的疝修补方法,适用于腹壁缺损不严重的各种腹外侧及复发疝。 相似文献
58.
Duranti R Sanna A Romagnoli I Nerini M Gigliotti F Ambrosino N Scano G 《Pflügers Archiv : European journal of physiology》2004,448(2):222-230
We hypothesized that walking at increased speed or increasing gradient might have different effects on chest wall kinematics and respiratory muscle power components, and contribute differently to respiratory effort sensation. We measured the volumes of chest wall compartments by optoelectronic plethysmography, esophageal, gastric and transdiaphragmatic (P
di) pressures, and the sensation of the respiratory effort by a Borg scale in five normal subjects walking both at ascending gradient with constant speed (AG) and at ascending speed with constant gradient (AS). Chest wall kinematics, evaluated by displacement of chest wall compartments, did not show any significant difference between AS and AG. Muscle power, calculated as the product of mean flow and mean pressure, increased similarly, but its partitioning into pressure and velocity of shortening differed in the two modes. A greater increase in the pressure developed by the abdominal muscles (P
abm) (4.06-fold), and in the velocity of shortening of both rib cage inspiratory muscles (v
rcm,i) (2.01-fold) and the diaphragm (v
di) (1.90-fold) was associated with a lower increase in the pressure developed by the rib cage inspiratory muscles (P
rcm,i) (1.24-fold) and P
di (0.99-fold) with AG. Instead, with AS, a lower increase in P
abm (2.12-fold), v
rcm,i (1.66-fold) and v
di (1.54-fold) was associated with a greater increase in P
rcm,i (1.56-fold) and P
di (1.97-fold). A combination of P
abm and v
di during AG (Wald 2=23.19, P<0.0000), with the addition of P
rcm,i during AS (Wald 2=29.46, P<0.0000), was the best predictor of Borg score. In conclusion, the general strategy adopted by respiratory centers during different walking modes does not differ in terms of ventilation, chest wall kinematics, and respiratory muscle power production, whereas it does in terms of partitioning of power into pressure and velocity of shortening, and respiratory muscle contribution to respiratory effort sensation. Combinations of different patterns of flow and pressure generation made the respiratory effort sensation similar during AS and AG modes. 相似文献
59.
Keishi Okamoto Kodo Kodama Katsushi Kawai Tetsuaki Wakebe Kazunobu Saiki Seiji Nagashima 《Annals of anatomy》2006,188(1):49-53
Among cases that had multiple renal arteries on one side, an inferior supernumerary renal artery was found in 24/270 cases (ca. 9%) on the right and in 19/270 cases (ca. 7%) on the left, together with the usual renal artery. We have noticed that there are correlations between their levels of origin from the aorta and their positional relation to the ureter and the inferior vena cava (IVC). An inferior supernumerary renal artery (InfRA) of lower origin passes in front of the IVC and behind the ureter. An InfRA of middle origin passes in front of both the IVC and the ureter. An InfRA of upper origin passes behind the IVC and in front of the ureter or renal pelvis. In addition there was a tendency for the lower origin type to have an ureteric branch, while the middle and upper origin types had a gonadal branch. These findings suggest that different derivations lead to the inferior supernumerary renal arteries. 相似文献
60.
Immunodeficiency in RFM/(T6xRFM)F1 mouse chimaeras with lethal host-versus-graft syndrome.
下载免费PDF全文
![点击此处可从《Clinical and experimental immunology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Rather than central tolerance, the perinatal inoculation of related F1 hybrid spleen cells into inbred mice may result in host-versus-graft (HVG) reactions manifested as transient autoimmunity, or as a lethal immunodeficiency syndrome. RFM/(T6xRFM)F1 chimaeras with lethal disease die in 30 days with lymphosplenomegaly, immune complexes and impaired immune responses. The present studies used in vitro proliferation assays to show that the HVG reaction caused hyperplasia sufficient to account for the lymphosplenomegaly, while also causing severe impairment of splenic and nodal cell responses to concanavalin A (Con A) and to bacterial lipopolysaccharide (LPS). By 25 days, HVG mice could not distinguish between self and non-self as judged by mixed lymphocyte reactions (MLR) to RFM, (T6xRFM)F1 and third party A/J cells. There were no indications that host cells reactive to F1 donor cells had undergone clonal deletion, anergy or expansion. Flow cytometry revealed that donor T lymphocytes achieved stable engraftment, mostly in the nodes, despite the HVG reaction. Taken together with previous observations, these studies showed that HVG reactions in young parent F1/chimaeras can result in an immunodeficiency state which is characterized by an early appearing, profound and persistent impairment of both host and donor T and B cell functions. The results suggest that HVG reactions can contribute directly to immune deficits seen after clinical allogeneic bone marrow transplantation. 相似文献