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   7755篇
  免费   363篇
  国内免费   41篇
耳鼻咽喉   38篇
儿科学   73篇
妇产科学   157篇
基础医学   976篇
口腔科学   213篇
临床医学   448篇
内科学   1628篇
皮肤病学   72篇
神经病学   671篇
特种医学   222篇
外科学   1659篇
综合类   31篇
预防医学   310篇
眼科学   386篇
药学   564篇
中国医学   9篇
肿瘤学   702篇
  2023年   36篇
  2022年   55篇
  2021年   124篇
  2020年   70篇
  2019年   96篇
  2018年   123篇
  2017年   104篇
  2016年   131篇
  2015年   100篇
  2014年   190篇
  2013年   247篇
  2012年   356篇
  2011年   411篇
  2010年   208篇
  2009年   227篇
  2008年   365篇
  2007年   383篇
  2006年   352篇
  2005年   432篇
  2004年   378篇
  2003年   389篇
  2002年   354篇
  2001年   250篇
  2000年   276篇
  1999年   238篇
  1998年   101篇
  1997年   89篇
  1996年   77篇
  1995年   63篇
  1994年   66篇
  1993年   60篇
  1992年   177篇
  1991年   164篇
  1990年   145篇
  1989年   138篇
  1988年   145篇
  1987年   135篇
  1986年   135篇
  1985年   125篇
  1984年   92篇
  1983年   55篇
  1982年   35篇
  1980年   31篇
  1979年   46篇
  1978年   33篇
  1977年   33篇
  1974年   35篇
  1972年   31篇
  1970年   29篇
  1969年   30篇
排序方式: 共有8159条查询结果,搜索用时 484 毫秒
51.
52.
A 28-year-old woman had developed chronic, recurrent, visual disturbance (bilateral), and girdle sensation at Th 5-6. She was admitted to our hospital because of left visual disturbance, distal limb weakness on right side, and numbness of four extremities. The neurological examination revealed decreased visual acuity of the left eye with abnormality of the optic disk, moderate muscle weakness of the right upper and lower extremities, absent tendon reflexes and paresthesia on distal portions of the four limbs. Laboratory examinations disclosed the titration of anti-myelin associated glycoprotein (MAG) antibody (IgM) and CSF protein was elevated (104 mg/dl). Motor nerve conduction studies revealed conduction block in more than one nerve. The conduction velocities in the upper and lower extremities were all diminished. P100 latency was prolonged by flash visual evoked potential (VEP) studies. N13-N20 interpeak latency of somatosensory evoked potential (SEP) of median nerve was also prolonged. She was treated with steroid pulse therapy, followed by an oral dose of 30 mg/day of prednisolone. Her symptoms resolved completely three months later, and multifocal conduction block subsided on electrophysiological study. There are some cases of multiple sclerosis with multifocal conduction block, but such a case is very rare in Japan. We discussed the pathogenic mechanisms of these conditions, and we conclude that we must take notice of demyelinating neuropathy in multiple sclerosis and that nerve conduction studies are useful for detecting them.  相似文献   
53.
Percutaneous transluminal angioplasty (PTA) of the vertebral artery was performed with an autoperfusion balloon catheter in five patients. There were no complications in the form of embolic episodes or neurological deficits due to brain ischaemia during inflation. In critical cases with insufficient collateral circulation during temporary occlusion, the use of an autoperfusion balloon catheter may expand the indications for PTA in patients with ischaemic cerebrovascular disease.  相似文献   
54.
Although various experimental models of mental illness, such as anxiety and depression, have been developed, little attention has been paid to male psychogenic impotence. Since sociopsychological factors are presumed to play an important role in many cases of human impotence, an animal model of psychogenic impotence is needed to satisfy such validity. From an ethological viewpoint, we have recently developed new animal models for psychogenic impotence using sociopsychological manipulations, that is, social deprivation and social conflict. This review focused only on the methodology and the actions of drugs on such copulatory disorder induced by social stress. Possible brain mechanisms underlying stress-induced copulatory disorder were also considered.  相似文献   
55.
We report here that loss of the Sprouty2 gene (also known as Spry2) in mice resulted in enteric nerve hyperplasia, which led to esophageal achalasia and intestinal pseudo-obstruction. Glial cell line-derived neurotrophic factor (GDNF) induced hyperactivation of ERK and Akt in enteric nerve cells. Anti-GDNF antibody administration corrected nerve hyperplasia in Sprouty2-deficient mice. We show Sprouty2 to be a negative regulator of GDNF for the neonatal development or survival of enteric nerve cells.  相似文献   
56.

Background  

Maharishi Amrit Kalash (MAK) 5, one of the Ayurvedic food supplements, belongs to a group of substances known as Rasayana. MAK5 and other Rasayanas are believed to enhance the body's resistance to infections and disease, and enhance longevity. In this study, we determined the effects of administration of MAK5, one of the Ayurvedic food supplements on immune functions in young and old mice.  相似文献   
57.
We have prospectively analyzed three antigens for serodiagnosis of tuberculosis (TB). These antigens were tuberculous glycolipid antigen, lypoarabinomannan polysaccharide antigen, and antigen 60 (A60), which was derived from purified protein derivatives. Of the 131 patients with active pulmonary TB, 57 were both smear and culture negative and 14 had chronic active pulmonary TB that remained smear positive for >12 months of chemotherapy. One hundred twenty healthy adults were controls. The percentages of patients positive in all three tests were 58.8% for smear-positive active pulmonary TB and 71.4% for chronic active pulmonary TB. When the results of the three serodiagnostic tests were evaluated in combination, the sensitivity increased to 91.5% in patients with active pulmonary TB and to 86.0% in smear- and culture-negative patients. The false-positive rate of the three-test combination was 12.5% in the healthy control groups. In conclusion, it was not possible to detect all of the antibodies against antigenic substances in the cell walls of the tuberculous bacilli in the sera of all TB patients by using available serodiagnostic tests. However, the combined use of tests with three separate antigens maximizes the effectiveness of serodiagnosis.  相似文献   
58.
Bacteroides forsythus is a gram-negative, anaerobic, fusiform bacterium and is considered to be an etiological agent in periodontal disease. A lipoprotein fraction prepared from B. forsythus cells by Triton X-114 phase separation (BfLP) activated human gingival fibroblasts and a human monocytic cell line, THP-1, to induce interleukin-6 production and tumor necrosis factor alpha production. BfLP was found to be capable of inducing nuclear factor-kappaB translocation in human gingival fibroblasts and THP-1 cells. By using Chinese hamster ovary K1 cells transfected with Toll-like receptor genes together with a nuclear factor-kappaB-dependent CD25 reporter plasmid, it was found that signaling by BfLP was mediated by Toll-like receptor 2 but not by CD14 or Toll-like receptor 4. BfLP induced apoptotic cell death in human gingival fibroblasts, KB cells (an oral epithelial cell line), HL-60 cells (a human myeloid leukemia cell line), and THP-1 cells but not in MOLT4 cells (a T-cell leukemia cell line). Caspase-8, an initiator caspase in apoptosis, was found to be activated in these cells in response to BfLP stimulation. Thus, this study suggested that BfLP plays some etiological roles in oral infections, especially periodontal disease, by induction of cell activation or apoptosis.  相似文献   
59.
Male Sprague-Dawley rats were fed for 4-5 weeks a choline-devoid diet containing 0.1% DL-ethionine. Preparations of nonparenchymal epithelial cells, enriched in oval cells, were isolated from the livers of these animals and were placed in culture. Six lines of hepatic epithelial cells were thus established. The lines underwent transformation after several passages, became tumorigenic in nude mice and 3 lines also in rats of the same strain of origin of the isolated cells. The tumors were uniformly highly anaplastic carcinomas. Preliminary morphologic, cytologic, and cytochemical results were consistent with the tumoral cells being hepatocytelike cells. These findings are viewed and discussed in terms of the cellular source, in vivo, of longterm cultures of rat liver epithelial cells, and in relation to a possible role of hepatic nonparenchymal epithelial cells in the process of hepatocellular tumor induction by chemical carcinogens.  相似文献   
60.
 Vascular endothelial growth factor (VEGF), a potent angiogenic and vascular permeability factor, may be important as a mediator of brain tumour progression. However, it is still not clear whether VEGF plays a causative role in the early stage of glioma development. We investigated the relationship between VEGF protein expression (as assayed by immunohistochemistry) and different morphological parameters reflecting tumour progression (tumour diameter, vascular density and vascular diameter) in tumours at various stages. As a tumour model, ethylnitrosourea (ENU)-induced rat malignant astrocytoma was used. Tumours were classified by size and level of vascularity estimated by the von Willebrand factor (vWF) staining. Tumours less than 10 mm in diameter were designated early stage neoplastic lesions. All 34 early astroglial tumours were found to be VEGF positive. Increase in the VEGF immunopositive rate of tumour cells correlated significantly with increase in vascular density and vascular diameter. We suggest that VEGF induces angiogenesis and growth of microvessels, promoting growth of the early stage malignant astrocytoma. Received: 7 October 1997 / Accepted: 9 June 1998  相似文献   
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