首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6382篇
  免费   374篇
  国内免费   55篇
耳鼻咽喉   38篇
儿科学   189篇
妇产科学   73篇
基础医学   1071篇
口腔科学   142篇
临床医学   408篇
内科学   1654篇
皮肤病学   190篇
神经病学   501篇
特种医学   210篇
外科学   705篇
综合类   14篇
预防医学   259篇
眼科学   211篇
药学   503篇
中国医学   24篇
肿瘤学   619篇
  2023年   51篇
  2022年   117篇
  2021年   194篇
  2020年   91篇
  2019年   96篇
  2018年   171篇
  2017年   139篇
  2016年   155篇
  2015年   161篇
  2014年   248篇
  2013年   261篇
  2012年   379篇
  2011年   473篇
  2010年   279篇
  2009年   235篇
  2008年   432篇
  2007年   467篇
  2006年   424篇
  2005年   485篇
  2004年   396篇
  2003年   381篇
  2002年   370篇
  2001年   64篇
  2000年   49篇
  1999年   70篇
  1998年   60篇
  1997年   43篇
  1996年   43篇
  1995年   46篇
  1994年   49篇
  1993年   28篇
  1992年   37篇
  1991年   39篇
  1990年   31篇
  1989年   33篇
  1988年   27篇
  1987年   21篇
  1986年   22篇
  1985年   13篇
  1984年   16篇
  1983年   12篇
  1982年   10篇
  1981年   12篇
  1980年   6篇
  1979年   13篇
  1978年   8篇
  1977年   6篇
  1975年   5篇
  1974年   5篇
  1973年   5篇
排序方式: 共有6811条查询结果,搜索用时 15 毫秒
91.
The large Japanese wood mouse (Apodemus speciosus) is common, but endemic to Japan, and its population structure was affected by habitat fragmentation because of urbanization. It suggested that the species might be one of the important models for the conservation of ecosystems and biodiversity affected by humans, including the effect of radioactive discharge caused by nuclear power plant accidents at Fukushima. We developed and characterized 25 novel polymorphic microsatellite markers from the next-generation sequencing data in an effort to provide an effective tool for genetic studies on this species. In 8 individuals from Aomori, Japan, the number of alleles and expected heterozygosities ranged from 5 to 13 and from 0.795 to 0.991, respectively, suggesting the availability of these markers for genetic studies in this species.  相似文献   
92.
The Otton frog (Babina subaspera) and Holst’s frog (Babina holsti) are both endangered sister species belonging to family Ranidae. For extensive genetic and ecological research of these species, we isolated and characterized 8 new microsatellite loci of the Otton frog and validated cross-amplification in Holst’s frog along with 8 previously reported loci. The total number of alleles and the expected heterozygosity of newly isolated loci in the Otton frog population ranged from 5 to 12 and from 0.620 to 0.905, respectively. We also confirmed cross-amplification in 4 of the new loci and in all previously reported loci in Holst’s frog with the same level of polymorphism as the Otton frog. Our findings suggest that these novel loci will be applicable for conservation genetic studies across varying scales.  相似文献   
93.
94.
Congenital prepubic sinus is a rare congenital anomaly situated in the midline of the lower abdomen. We report a case of congenital prepubic sinus, closely associated with a urachal remnant. Preoperative magnetic resonance imaging showed clearly that the sinus tracked the urachus caudally. This finding supports the theory that the anomaly is caused by abnormal remnant tissue originating from the cloacal membrane, which tracks the allantois duct caudally along with fetal longitudinal growth.  相似文献   
95.
Although fibrin sealant (FS) has an advantage of high biocompatibility, its adhesive force and sealing effect have been generally considered to be inadequate. In the present study, a high adhesive force and sealing effect were obtained by first rubbing fibrinogen solution into the target tissue, attaching polyglycolic acid (PGA) felt to the treated area, and finally spraying it with FS. This method was compared with three conventional FS application methods and a method using fibrin glue-coated collagen fleece. The adhesive force resulting from the present method was 12 times higher than that for the sequential application method, 4.5 times higher than the spray method, 2.5 times higher than the rubbing and spray method, and 2.2 times higher than the use of fibrin glue-coated collagen fleece. The high adhesive force of FS with PGA felt seemed to be due the high fibrin content of the fibrin gel (FG). Light and electron microscopic observations suggested that the formation of FG in closer contact with the muscle fibers was a factor contributing to this superior adhesive force. Comparison of the sealing effect of the present method with other methods using various biomaterials in combination with FS showed that the sealing effect of FS with PGA felt was 1.4 times higher that of polyglactin 910, 1.8 times that of polytetrafluoroethylene, and 6.7 times that of oxidized regenerated cellulose.  相似文献   
96.

Background

Venous malformations (VM) of lower extremities have characteristic symptoms, especially swelling, pain at rest or with dependence, or in the morning, or with exertion. Sclerotherapy has been applied and has been showed to alleviate the associated signs and symptoms. The aim of this study is to evaluate the outcomes of ethanol sclerotherapy for VM of lower extremities.

Methods

The 21 patients of intramuscular VM of the lower extremities, who received percutaneous sclerotherapy using absolute ethanol in our institute, were reviewed retrospectively. The average age at the time of the initial diagnosis was 18.6 years, and average follow-up period after last sclerotherapy is 19.4?±?13.5 months. The postinterventional changes of the associated signs and symptoms were evaluated by utilizing original VM scoring system.

Results

The average number of sclerotherapy sessions was 2.6 times per case. The average total amount of ethanol used in each patient was 41.3 ml. Sclerotherapy reduced the associated signs and symptoms in many of the patients (n?=?19/21). Preinterventional VM score as the overall baseline status was 10, and the average VM score after sclerotherapy was 4.1. There was no inverse correlation between the amount of ethanol used and the VM score. In seven cases treated more than three times, reverse correlation between the “VM score” and the number of sclerotherapy sessions was demonstrated (p?<?0.05, ρ?=?0.8214).

Conclusions

The characteristic symptoms and signs of the VM were improved by sclerotherapy. More than three sessions of ethanol sclerotherapy improved the overall status of extensive intramuscular VM in lower extremities. Level of Evidence: Level IV, therapeutic study.  相似文献   
97.
98.

Background

Although schizophrenia and major depressive disorder (MDD) differ on a variety of neuroanatomical measures, a diagnostic tool to discriminate these disorders has not yet been established. We tried to identify structural changes of the brain that best discriminate between schizophrenia and MDD on the basis of gray matter volume, ventricle volume, and diffusion tensor imaging (DTI).

Method

The first exploration sample consisted of 25 female patients with schizophrenia and 25 females with MDD. Regional brain volumes and fractional anisotropy (FA) values were entered into a discriminant analysis. The second validation sample consisted of 18 female schizophrenia and 16 female MDD patients.

Results

The stepwise discriminant analysis resulted in correct classification rates of 0.80 in the schizophrenic group and 0.76 in MDD. In the second validation sample, the obtained model yielded correct classification rates of 0.72 in the schizophrenia group and 0.88 in the MDD group.

Conclusion

Our results suggest that schizophrenia and MDD have differential structural changes in the examined brain regions and that the obtained discriminant score may be useful to discriminate the two disorders.  相似文献   
99.
Alpha2-macroglobulin is a protease inhibitor that enhances procoagulant properties via the neutralization of plasmin, plasminogen activators and metalloproteinases. Additionally, alpha2-macroglobulin is thought to be involved in inflammatory reactions as a carrier protein for interleukin-6 (IL-6). The objective of this study was to evaluate the usefulness of alpha2-macroglobulin as a biomarker for cerebrovascular diseases. Patients with acute ischemic stroke (n = 159; 93 male and 66 female, 71.6 ± 10.3 years) and patients with no previous history of stroke (n = 77; 38 male and 39 female, 70.7 ± 9.5 years) were consecutively enrolled in this study. White matter lesions were assessed via the fluid-attenuated inversion recovery image of magnetic resonance images using the Fazekas classification. The serum alpha2-macroglobulin levels were measured by nephelometry. The serum alpha2-macroglobulin levels at admission in patients with acute ischemic stroke were higher than those in the control patients (230.2 ± 73.7 vs. 205.0 ± 55.8 mg/dl, p = 0.009). The serum alpha2-macroglobulin levels were positively correlated with age and the severity of the white matter lesions (R 2 = 0.048, p < 0.001 and R 2 = 0.058, p < 0.001, respectively), although there was no significant association between serum alpha2-macroglobulin levels and IL-6 levels. In addition, multivariate analysis showed that increased serum alpha2-macroglobulin levels were independently associated with the severity of white matter lesions [standardized partial regression coefficient (β) 0.102, p = 0.026]. Increased serum alpha2-macroglobulin levels might be involved in the pathophysiology of acute ischemic stroke. Furthermore, serum alpha2-macroglobulin levels, which were associated with high-grade white matter lesions, may reflect the chronic pathophysiological condition of cerebral small vessel disease.  相似文献   
100.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号