全文获取类型
收费全文 | 27323篇 |
免费 | 2913篇 |
国内免费 | 45篇 |
专业分类
耳鼻咽喉 | 340篇 |
儿科学 | 868篇 |
妇产科学 | 524篇 |
基础医学 | 3608篇 |
口腔科学 | 573篇 |
临床医学 | 3282篇 |
内科学 | 4797篇 |
皮肤病学 | 255篇 |
神经病学 | 2915篇 |
特种医学 | 1012篇 |
外科学 | 4327篇 |
综合类 | 700篇 |
一般理论 | 5篇 |
预防医学 | 3009篇 |
眼科学 | 522篇 |
药学 | 1691篇 |
中国医学 | 17篇 |
肿瘤学 | 1836篇 |
出版年
2021年 | 362篇 |
2020年 | 221篇 |
2019年 | 402篇 |
2018年 | 521篇 |
2017年 | 381篇 |
2016年 | 377篇 |
2015年 | 445篇 |
2014年 | 608篇 |
2013年 | 1003篇 |
2012年 | 1342篇 |
2011年 | 1295篇 |
2010年 | 746篇 |
2009年 | 731篇 |
2008年 | 1219篇 |
2007年 | 1186篇 |
2006年 | 1154篇 |
2005年 | 1066篇 |
2004年 | 1104篇 |
2003年 | 1050篇 |
2002年 | 903篇 |
2001年 | 900篇 |
2000年 | 927篇 |
1999年 | 742篇 |
1998年 | 371篇 |
1997年 | 320篇 |
1996年 | 340篇 |
1995年 | 319篇 |
1994年 | 268篇 |
1993年 | 312篇 |
1992年 | 652篇 |
1991年 | 637篇 |
1990年 | 608篇 |
1989年 | 610篇 |
1988年 | 582篇 |
1987年 | 601篇 |
1986年 | 527篇 |
1985年 | 526篇 |
1984年 | 403篇 |
1983年 | 357篇 |
1982年 | 236篇 |
1981年 | 218篇 |
1980年 | 206篇 |
1979年 | 363篇 |
1978年 | 202篇 |
1977年 | 209篇 |
1976年 | 231篇 |
1975年 | 184篇 |
1974年 | 240篇 |
1973年 | 228篇 |
1972年 | 187篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
John G. Larkin George G. Thompson Gordon Scobie Joan E. Drennan Martin J. Brodie 《Epilepsia》1991,32(5):729-734
Interaction with adenosine A1 receptors is a possible contributory mechanism to the anticonvulsant effects of carbamazepine (CBZ) and the dihydropyridine calcium antagonists. We measured the binding of [3H]cyclohexyladenosine to adenosine A1 receptors in mouse brain stem, cerebellum, and cortex after oral administration of nifedipine, nimodipine (NMD), and CBZ for 7 days and compared the results with binding in control mice. Equilibrium dissociation constant (Kd) and receptor numbers (Bmax) were calculated using Scatchard and saturation isotherm analyses. Mean Kds (SEM) in control brain stem, cerebellum, and cortex were 2.09 (0.31), 2.39 (0.2), and 3.12 (0.28) nM, respectively. Results of Bmax for the same areas were 188 (26), 280 (24), and 449 (54) fmol/mg protein. Nifedipine (p less than 0.005) and NMD (p less than 0.02) raised the Kd of A1 receptors only in the cerebellum, and CBZ increased cerebellar Bmax (p less than 0.05). These minor effects on A1 receptors in CF1 mice, when given in doses previously shown to have anticonvulsant properties in these animals, do not suggest that alteration in A1 receptor activity is an important mechanism for the anticonvulsant effects of these drugs. 相似文献
42.
Cleft closure for the treatment of unhealed perineal sinus 总被引:2,自引:0,他引:2
OBJECTIVE: Despite improvements in surgical practice, persistent perineal wound sinus is still a common complication after proctectomy. This study presents the success of a modified cleft closure technique in dealing with this problem. METHODS: From May 1997 patients with a persistent perineal sinus after surgery underwent a cleft closure - similar to that performed for patients with pilonidal sinus disease. RESULTS: Eight patients (6 male, 2 female) with an average age of 52 years underwent a cleft closure for a persistent perineal sinus after surgery. Four patients had undergone a proctocolectomy (ulcerative colitis), 2 an abdominoperineal excision of the rectum (adenocarcinoma) and 2 a proctectomy (1 Crohn's disease, 1 complication of diverticular disease). Symptoms had been present for an average of 41 months (range 5-152 months) and 3 patients had undergone other procedures attempted previously to deal with the problem. The first three patients had the procedure as an inpatient with an average stay of 4.7 days. The next 5 patients had the procedure as a day case (2 local anaesthetic, 3 general anaesthetic). Two patients developed a postoperative wound infection and all but one wound had healed completely by 8 weeks. In this patient the procedure was repeated to achieve healing. There was no other associated morbidity and no postoperative deaths. There have been no recurrences to date. CONCLUSION: Modified cleft closure for persistent perineal sinus is a simple procedure with low morbidity that can be performed under local anaesthetic in the day surgery unit. 相似文献
43.
Richard B Thompson Ewout J van den Bos Bryce H Davis Yoshihisa Morimoto Damian Craig Brad S Sutton Donald D Glower Doris A Taylor 《The Journal of heart and lung transplantation》2005,24(2):205-214
BACKGROUND: Pre-clinical and clinical studies suggest that transplantation of bone marrow-derived stem cells can improve global cardiac function. However, no quantitative assessment of regional systolic contraction and correlation with phenotype has been made. Therefore, we used our model of cryoinfarcted rabbit myocardium for intracardiac transplantation of a mixed population of bone marrow-derived cells and assessed both regional function and myogenic conversion of the cells. METHODS: Nineteen New Zealand white rabbits underwent cryoinjury of the left ventricle. Autologous bone marrow (BM) cells were expanded in vitro. After 2 weeks, either 1 x 10(8) mixed BM-derived progenitor cells (BM group, n = 11) or vehicle (control group, n = 8) were injected into the cryoinjured region. Regional systolic function was measured using micromanometry and sonomicrometry before and 4 weeks after cell injection; cell phenotype was evaluated histologically. RESULTS: All animals in the BM group significantly improved both systolic shortening (0.11 +/- 0.7 vs -0.05 +/- 0.05 mm in the control group, p < 0.05) and regional stroke work when compared with control (9.6 +/- 2.4 vs -1.2 +/- 1.2 mm . mm Hg, p < 0.003). In addition, the BM group had improved global diastolic function, as measured by minimum dP/dt and end-diastolic pressure. On histologic assessment, BM cells differentiated toward a myogenic phenotype. CONCLUSIONS: Transplanting a mixed population of marrow-derived cells that can adopt a myogenic phenotype improves regional contractility and diastolic relaxation after myocardial infarction. 相似文献
44.
45.
46.
The many uses of the U tube 总被引:2,自引:0,他引:2
U tube placement was employed as an adjunct to complicated biliary procedures in 14 patients. We found the transhepatic tubes to be useful for stenting biliary anastomoses, maintaining biliary drainage, delivering localized irradiation, and acting as permanent external conduits. The tubes remained in placed an average of 15 months and as long as 40 months. The frequency of cholangitis was minimized by frequent tube exchange. The U-shaped configuration makes tube exchange easy and inexpensive to perform. 相似文献
47.
48.
M L Cibull M E Thompson L Smith C D Jennings M A Doukas E J Pavlik D E Powell 《American journal of hematology》1987,24(3):293-299
The emergence of a near-haploid clone of cells in blast phase chronic myelogenous leukemia is an unusual event. We report such a case and review eight other cases described in the English literature. The significance of the substantial loss of genetic material is discussed as is the phenotypic and genotypic heterogeneity observed in this group of patients. 相似文献
49.
The goal of the present study is to develop a technique for laparoscopic aortobifemoral bypass.Piglets weighing between 60 and 78 kg were anesthetized with halothane. The lateral retroperitoneal approach was preferred to the more familiar anterior transperitoneal approach and was successfully completed in 19 piglets. The piglets were placed in the right lateral decubitus position. The first port (2 cm) was inserted halfway between the tip of the 12th rib and the iliac crest. Four other trocars were placed in the retroperitoneum after balloon inflation had allowed creation of a space which permitted visualization of the aorta from the left renal artery down to the aorto-iliac junction. After evacuation of the retropneumoperitoneum, the cavity was maintained using an abdominal lift device and a retractor.Using this approach, we performed four aortobifemoral bypasses (end-to-end aortic anastomosis) after conventional intravenous heparinization (100 IU/kg) in less than 4 h. Blood loss did not exceed 250 ml and the hematocrit remained stable. Postmortem evaluation of the grafts revealed they were positioned as in a conventional bypass, their limbs having followed in the created retroperitoneal tunnels along the path of the native arteries. No mortality occurred before sacrifice of the animals. We believe that this first performed series of totally retroperitoneal laparoscopic aortobifemoral bypasses in the porcine model is useful in preparation for human application due to the anatomical similarities in the periaortic region. 相似文献
50.
G. Bradley Schaefer James N. Thompson John B. Bodensteiner James M. McConnell William J. Kimberling Charles T. Gay William D. Dutton David C. Hutchings Stanton B. Gray 《Annals of neurology》1996,39(3):382-385
There are conflicting reports on the relationship between cerebellar vermal lobule hypoplasia and autism. Using quantitative magnetic resonance image analysis, we measured the cerebellar vermis in 125 normal individuals with a broad age range and 102 patients with a variety of neurogenetic abnormalities. We conclude that hypoplasia of cerebellar vermal lobules VI and VII is a nonspecific finding that even occurs in several conditions without autistic behavior. This suggests that it is not a specific neuroanatomical marker for autism, nor is cerebellar dys- genesis likely to be solely responsible for clinical autistic behaviors. 相似文献