全文获取类型
收费全文 | 9136篇 |
免费 | 748篇 |
国内免费 | 59篇 |
专业分类
耳鼻咽喉 | 204篇 |
儿科学 | 290篇 |
妇产科学 | 209篇 |
基础医学 | 1141篇 |
口腔科学 | 201篇 |
临床医学 | 802篇 |
内科学 | 1577篇 |
皮肤病学 | 191篇 |
神经病学 | 1035篇 |
特种医学 | 460篇 |
外科学 | 1264篇 |
综合类 | 190篇 |
一般理论 | 7篇 |
预防医学 | 913篇 |
眼科学 | 472篇 |
药学 | 498篇 |
中国医学 | 1篇 |
肿瘤学 | 488篇 |
出版年
2021年 | 152篇 |
2019年 | 104篇 |
2018年 | 116篇 |
2017年 | 81篇 |
2016年 | 103篇 |
2015年 | 117篇 |
2014年 | 199篇 |
2013年 | 274篇 |
2012年 | 397篇 |
2011年 | 405篇 |
2010年 | 243篇 |
2009年 | 240篇 |
2008年 | 380篇 |
2007年 | 391篇 |
2006年 | 371篇 |
2005年 | 402篇 |
2004年 | 421篇 |
2003年 | 364篇 |
2002年 | 333篇 |
2001年 | 314篇 |
2000年 | 299篇 |
1999年 | 313篇 |
1998年 | 85篇 |
1997年 | 94篇 |
1996年 | 80篇 |
1995年 | 93篇 |
1994年 | 83篇 |
1993年 | 77篇 |
1992年 | 192篇 |
1991年 | 195篇 |
1990年 | 203篇 |
1989年 | 161篇 |
1988年 | 161篇 |
1987年 | 187篇 |
1986年 | 165篇 |
1985年 | 197篇 |
1984年 | 120篇 |
1983年 | 99篇 |
1982年 | 81篇 |
1981年 | 80篇 |
1980年 | 77篇 |
1979年 | 113篇 |
1978年 | 111篇 |
1977年 | 82篇 |
1976年 | 84篇 |
1975年 | 81篇 |
1974年 | 97篇 |
1973年 | 96篇 |
1972年 | 82篇 |
1970年 | 86篇 |
排序方式: 共有9943条查询结果,搜索用时 890 毫秒
91.
Rania M Seliem Jonathan K Freeman Richard H Steingart Robert P Hasserjian 《Applied immunohistochemistry & molecular morphology》2006,14(1):18-23
Rituximab is a chimeric monoclonal antibody that recognizes the CD20 antigen and is used to treat B-cell non-Hodgkin lymphoma (B-NHL). Few studies have been published examining the use of antibody panels to evaluate B-NHL treated with rituximab. The authors performed a retrospective analysis of immunophenotypic changes and clinical outcome in 18 patients with B-NHL following rituximab therapy. The intensity of CD20 expression was evaluated by flow cytometry and/or immunohistochemistry, before and after rituximab therapy; the latter samples were taken 5 to 12 months after initiating rituximab therapy (median 7 months). Nine of the 18 patients (50%) achieved complete or partial clinical remission and did not have morphologic evidence of lymphoma in the post-therapy samples. The other nine patients (50%) had persistent disease. Two patterns of CD20 expression were noted in the post-therapy samples: unchanged expression of CD20 in neoplastic cells (4/9 cases) and loss of or a significant decrease in detected CD20 expression in neoplastic cells (5/9 cases). These results show that in many cases of B-NHL persisting after rituximab therapy, CD20 expression decreases or is lost, raising the possibility of deletion or expression modulation of the CD20 gene in neoplastic cells. This study also underscores the importance of using a panel of antibodies to evaluate rituximab-treated B-NHL. 相似文献
92.
Robert J. Stephens Marlene F. Sloan Michael J. Evans Gustave Freeman 《The American journal of pathology》1974,74(1):31-58
The epithelial response in the terminal bronchioles and alveoli was examined after exposure to approximately 0.5 and 0.9 ppm ozone (O3). Loss of ciliated cells from the terminal bronchiole was pronounced after 6 to 10 hours of exposure; however, nonciliated cells were resistant to injury from O3. In contrast, type 1 alveolar lining cells were very sensitive to O2 and were severely damaged or removed from significant areas of the proximal alveoli after as little as 2 hours of exposure to 0.5 ppm. The basement lamina was left devoid of an epithelium with the exception of type 2 cells, which were very resistant and retained a relatively normal appearance. Under continuous exposure, repair of the lesion area was accomplished in approximately 48 hours through proliferation of the type 2 cells. The new cells were cuboidal at first but subsequently became more squamous in appearance. Exposure for 8 to 10 hours followed by residence in clean air resulted in a proliferative response at 48 hours, about equal to that observed after continuous exposure. 相似文献
93.
One hundred four patients undergoing coronary bypass surgery were evaluated for psychiatric symptoms and their association with postoperative arrhythmias occurring within 48 hours after surgery. Patients high in type A behavior had increased risk of ventricular arrhythmias, while those scoring relatively high in depression and anxiety had fewer atrial arrhythmias than patients low in these measures. No significant association was found between postoperative arrhythmias and obesity, heavy tobacco use, or number of bypasses. A history of arrhythmias correlated significantly with postoperative arrhythmias. Anxious or depressed patients who deny their symptoms may be at increased risk for postoperative atrial arrhythmias. 相似文献
94.
Alon Peled Ofer Sarig Guangping Sun Liat Samuelov Chi A. Ma Yuan Zhang Tom Dimaggio Celeste G. Nelson Kelly D. Stone Alexandra F. Freeman Liron Malki Lucia Seminario Vidal Latha M. Chamarthy Valeria Briskin Janan Mohamad Mor Pavlovsky Jolan E. Walter Joshua D. Milner Eli Sprecher 《The Journal of allergy and clinical immunology》2019,143(1):173-181.e10
95.
1. The visual evoked response to a grating target of varying spatial frequency was examined for normal subjects and for subjects with meridional amblyopia. This condition, reduced visual resolution for specific target orientations, is associated with, and thought to result from, marked ocular astigmatism. 2. For normal subjects, the general relation between spatial frequency and the evoked response is similar to psychophysical contrast sensitivity data. Evoked response amplitudes to oblique gratings are typically reduced and this is analogous to the lower acuity for oblique compared to horizontal and vertical detail. 3. In addition to the oblique effect, the magnitude of the evoked response for meridional amblyopes depends upon grating orientation over most of the spatial frequency range tested (0-5-16 cycles/deg). The lowest evoked amplitude is found when stimulus grating orientation matches that for which acuity is reduced. 4. The evoked potentials spatial frequency response functions are qualitatively similar to contrast sensitivity functions determined with the same abnormal subjects. 5. From these results, it may be concluded that the physiological locus of meridional amblyopia is confined primarily to structures at or prior to the site of evoked potential generation. 相似文献
96.
97.
98.
Distinct roles of pattern recognition receptors CD14 and Toll-like receptor 4 in acute lung injury 总被引:4,自引:0,他引:4
下载免费PDF全文
![点击此处可从《Infection and immunity》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Acute lung injury (ALI) induced by lipopolysaccharide (LPS) is a major cause of mortality among humans. ALI is characterized by microvascular protein leakage, neutrophil influx, and expression of proinflammatory mediators, followed by severe lung damage. LPS binding to its receptors is the crucial step in the causation of these multistep events. LPS binding and signaling involves CD14 and Toll-like receptor 4 (TLR4). However, the relative contributions of CD14 and TLR4 in the induction of ALI and their therapeutic potentials are not clear in vivo. Therefore, the aim of the present study was to compare the roles of CD14 and TLR4 in LPS-induced ALI to determine which of these molecules is the more critical target for attenuating ALI in a mouse model. Our results show that CD14 and TLR4 are necessary for low-dose (300-microg/ml) LPS-induced microvascular leakage, NF-kappaB activation, neutrophil influx, cytokine and chemokine (KC, macrophage inflammatory protein 2, tumor necrosis factor alpha, interleukin-6) expression, and subsequent lung damage. On the other hand, when a 10-fold-higher dose of LPS (3 mg/ml) was used, these responses were only partially dependent on CD14 and they were totally dependent on TLR4. The CD14-independent LPS response was dependent on CD11b. A TLR4 blocking antibody abolished microvascular leakage, neutrophil accumulation, cytokine responses, and lung pathology with a low dose of LPS but only attenuated the responses with a high dose of LPS. These data are the first to demonstrate that LPS-induced CD14-dependent and -independent (CD11b-dependent) signaling pathways in the lung are entirely dependent on TLR4 and that blocking TLR4 might be beneficial in lung diseases caused by LPS from gram-negative pathogens. 相似文献
99.
Gatzoulis MA Freeman MA Siu SC Webb GD Harris L 《The New England journal of medicine》1999,340(11):839-846
BACKGROUND: Atrial flutter and atrial fibrillation are causes of morbidity in adults with an atrial septal defect. In this study, we attempted to identify risk factors for atrial flutter and fibrillation both before and after the surgical closure of an atrial septal defect. METHODS: We searched for preoperative and postoperative atrial flutter or fibrillation in 213 adult patients (82 men and 131 women) who underwent surgical closure of atrial septal defects because of symptoms, a substantial left-to-right shunt (ratio of pulmonary to systemic blood flow, >1.5:1), or both at Toronto Hospital between 1986 and 1997. RESULTS: Forty patients (19 percent) had sustained atrial flutter or fibrillation before surgery. As compared with the patients who did not have atrial flutter or fibrillation before surgery, those who did were older (59+/-11 vs. 37+/-13 years, P<0.001) and had higher mean pulmonary arterial pressures (25.0+/-9.7 vs. 19.7+/-8.2 mm Hg, P=0.001). There were no perioperative deaths. After a mean follow-up period of 3.8+/-2.5 years, 24 of the 40 patients (60 percent) continued to have atrial flutter or fibrillation. The mean age of these patients was greater than that of the 16 who converted to sinus rhythm (P=0.02). New-onset atrial flutter or atrial fibrillation was more likely to have developed at follow-up in patients who were older than 40 years at the time of surgery than in those who were 40 or younger (5 of 67 vs. 0 of 106, P=0.008). Late events (those occurring more than one month after surgery) included stroke in six patients (all but one with atrial flutter or fibrillation, one of whom died) and death from noncardiac causes in two patients. Multivariate analysis showed that older age (>40 years) at the time of surgery (P=0.001), the presence of preoperative atrial flutter or fibrillation (P<0.001), and the presence of postoperative atrial flutter or fibrillation or junctional rhythm (P=0.02) were predictive of late postoperative atrial flutter or fibrillation. CONCLUSIONS: The risk of atrial flutter or atrial fibrillation in adults with atrial septal defects is related to the age at the time of surgical repair and the pulmonary arterial pressure. To reduce the morbidity associated with atrial flutter and fibrillation, the timely closure of atrial septal defects is warranted. 相似文献
100.
Permanent impairment of embryo development by hydrosalpinges 总被引:6,自引:9,他引:6
Recent reports suggest a deleterious effect of hydrosalpinges on pregnancy
outcome for in-vitro fertilization (IVF) and improvement following surgical
treatment. We compared the effect of hydrosalpinx on pregnancy outcome in
286 patients having 348 IVF cycles and followed the development of
untransferred embryos for 7 days to determine if hydrosalpinges affect
oocyte quality or embryo development. The delivery rate per retrieval was
significantly lower for patients with hydrosalpinx, but was restored by
surgical treatment to that of patients without hydrosalpinx. However, the
implantation rate per embryo transferred and normal blastulation of
untransferred embryos, which were significantly decreased in patients with
hydrosalpinx, and growth arrest and degeneration of untransferred embryos,
which were significantly increased compared to patients without
hydrosalpinx, were not restored by surgical treatment of hydrosalpinges. We
conclude that surgical treatment of hydrosalpinges decreases early
pregnancy loss and improves pregnancy outcome, possibly by diminishing
reversible deleterious effects exerted on the endometrium. As we have seen
in our laboratory, hydrosalpinges may have a permanent negative influence
on ovarian function, follicular development and oocyte quality since
implantation of transferred embryos and normal blastulation of
untransferred embryos remain low, and in-vitro growth arrest and
degeneration remain high despite surgical treatment of hydrosalpinges.
相似文献