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   51606篇
  免费   3222篇
  国内免费   246篇
耳鼻咽喉   645篇
儿科学   1188篇
妇产科学   1234篇
基础医学   7157篇
口腔科学   1515篇
临床医学   5650篇
内科学   11099篇
皮肤病学   804篇
神经病学   5150篇
特种医学   1790篇
外科学   6429篇
综合类   327篇
一般理论   47篇
预防医学   3661篇
眼科学   809篇
药学   3495篇
  1篇
中国医学   59篇
肿瘤学   4014篇
  2023年   323篇
  2022年   634篇
  2021年   1146篇
  2020年   749篇
  2019年   988篇
  2018年   1205篇
  2017年   1080篇
  2016年   1266篇
  2015年   1321篇
  2014年   1753篇
  2013年   2528篇
  2012年   3826篇
  2011年   4009篇
  2010年   2380篇
  2009年   2171篇
  2008年   3331篇
  2007年   3621篇
  2006年   3238篇
  2005年   3300篇
  2004年   3027篇
  2003年   2828篇
  2002年   2590篇
  2001年   454篇
  2000年   376篇
  1999年   520篇
  1998年   574篇
  1997年   477篇
  1996年   419篇
  1995年   365篇
  1994年   319篇
  1993年   318篇
  1992年   266篇
  1991年   255篇
  1990年   232篇
  1989年   251篇
  1988年   228篇
  1987年   189篇
  1986年   193篇
  1985年   234篇
  1984年   201篇
  1983年   176篇
  1982年   212篇
  1981年   165篇
  1980年   146篇
  1979年   129篇
  1978年   134篇
  1977年   140篇
  1976年   100篇
  1975年   116篇
  1974年   90篇
排序方式: 共有10000条查询结果,搜索用时 298 毫秒
61.
62.
This paper describes a quick procedure for cadaveric liver graft retrieval during multiple organ harvesting. The technique is based on minimal preliminary dissection, absence of in situ direct portal perfusion, and en bloc removal of the liver and pancreas, with an aortic patch encompassing the coeliac trunk and superior mesenteric artery. The results of 110 pediatric liver transplantations with 109 organs harvested using this technique are reported. There were no graft harvesting injuries. The liver graft primary nonfunction rate was 4.5% (5/110). The 3-month retransplantation rate was 10%. The actual patient survival rates were 93% at 3 months and 90% at 1 year; actual graft survival rates were 85.5% and 78%, respectively. The technique described was at least as safe as conventional procedures. A major advantage of the procedure is its flexibility, which allows for the easily combined procurement of other organs (whole pancreas and intestine).  相似文献   
63.
Observations on time-dependent localization of tetra(3-hydroxyphenyl)porphin (3-THPP) in human malignant melanoma transplanted to athymic nude mice from 1 to 120 h after intraperitoneal (i.p.) 10 mg kg–1 b.w. administration were made by means of fluorescence microscopy. Fluorescence was found on the membrane of the melanoma cells and in the cytoplasm with a peak fluorescence intensity at 24 h post-injection of 3-THPP. The growth of the tumour cells was obviously inhibited at an early stage after PCT. Morphological changes of the tumour at various intervals after treatment by PCT with 3-THPP were also observed. Diffuse degeneration of the tumour cells with swelling of mitochondria and endoplasmic reticulum, heterochromatin aggregation and margination, etc., and subsequently diffuse necrosis with little or no the background of tumorous vascular response were found at an early stage after PCT. On the other hand, it was also observed that the necrosis of the melanoma areas was caused as a consequence of tumorous vascular injury at a later stage after PCT. Thus, two tumoricidal processes caused by PCT with 3-THPP were seen: a direct phototoxic action on tumour cells at an early stage after PCT and an indirect effect secondary to tumorous vascular injury at a later period after PCT.  相似文献   
64.
Summary A patient is described with a testicular Non-Hodgkin's Lymphoma (NHL) presenting with panhypopituitarism caused by a hypophyseal localization. A67Gallium scintigraphy showed avid uptake in the hypophyseal region. Obviously67Gallium could reach the tumor, by the intravenous route, which was the reason to treat the patient with intravenous chemotherapy. A complete remission was induced, which seems to be lasting (+ 25 months). As far as we know this is the first report of panhypopituitarism caused by a hypophyseal NHL in the hypophysis and successfully treated by intravenous chemotherapy.  相似文献   
65.
We report improvement in muscle strength in a patient with multifocal motor neuropathy (MMN) when given high-dose intravenous immunoglobin (i.v.-Ig) treatment. The patient had asymmetrical limb weakness, atrophy and absent or weak reflexes, but no sensory disturbances. Neurography showed multiple conduction blocks in peripheral motor nerves but no sensory nerve abnormalities. Serum and anti-GM1 antibodies were not found, however, the patient had serum antibodies against the glycolipid LK1, an epitope found both in glycolipid and also in some glycoproteins in peripheral nerve myelin. Muscle strength improved 5 days after i.v.-Ig therapy, and lasted about 10 weeks. Repeated courses of treatment resulted in similar improvement. This is, to our knowledge, the first patient reported with MMN found to have antibodies against the glycolipid LK1.  相似文献   
66.
Anionic polymerization of ?-caprolactam was initiated with the potassium salt of ?-caprolactam and accelerated with phenyl isocyanate, toluylene diisocyanate, 4,4′-diphenylmethane diisocyanate, some derivatives of these isocyanates (urethanes, ureas, and allophanates), or combinations of phenyl isocyanate with its derivatives at 150°C. The effect of individual structures on the polymerization kinetics and their contribution to the preparation of block copolymers of ?-caprolactam with hydroxy-terminated prepolymers, in-situ functionalized with diisocyanates, are discussed on the basis of a detailed analysis of time functions of polymer yield and degree of polymerization.  相似文献   
67.
As part of a nation-wide psychological autopsy we examined the differences in DSM-III-R mental disorders, recent life events and other characteristics between urban (n=143) and rural (n=85) completed suicides in a random sample of 229 cases from the National Suicide Prevention Project in Finland for the period 1987-1988. Psychoactive substance use disorders (48% vs. 34%), cluster B personality disorders (24% vs. 9%) and psychiatric comorbidity (66% vs. 42%) were found more commonly among urban than rural suicides. Urban suicides were also more often reported to be preceded by a recent separation (25% vs. 8%), whereas rural suicide victims tended to have lacked a close companion of the opposite sex (36% vs. 18%) and to have had physical disorders (56% vs. 40%). Overall, urban and rural suicides may vary with regard to the prevalence of some mental disorders, their comorbidity, and physical disorders, as well as the preceding life situation. This variation may also imply the need for differences in strategies for suicide prevention in each setting.  相似文献   
68.
Mice homozygous for the lpr mutation have B and T cell defects and develop autoantibodies, suggesting that lpr plays a role in their genesis. The lpr defect has been identified as a mutation in the apoptosis-associated Fas receptor (FasR) gene. To begin to define the role of FasR in B cells, we have surveyed FasR expression on B-lineage cells from early progenitors in the bone marrow through their maturation in the periphery. Contrary to some reports, we found that FasR is expressed on B cells at all stages of their development and is highest on germinal center B cells. FasR is not expressed on lpr/lpr-derived cells. These data are consistent with the idea that lpr/lpr mice have an intrinsic B cell defect that may be manifested in developing as well as peripheral B cells. An unexpected finding is that B-1 (CD5) B cells do not constitutively express FasR: FasR becomes detectable on B-1 B cells only after activation.  相似文献   
69.
70.
The histamine-storing neural system in adult and developing zebrafish (Danio rerio) was studied with immunocytochemical and chromatographical methods. Furthermore, the gene for histidine decarboxylase was partially cloned and its expression mapped with in situ hybridization. The histamine-storing neurons were only seen in the caudal hypothalamus, around the posterior recess of the diencephalic ventricle. Almost all parts of the brain, except the cerebellum, contained at least some histamine-immunoreactive fibres. The ascending projections had the rostral part of the dorsal telencephalon as a major target. Descending projections terminated in the torus semicircularis, central grey and inferior olive. A prominent innervation of the optic tectum, which has not been reported in other fish, was seen. The in situ hybridization gave a strong signal in cells with the same anatomical position as the histamine-immunoreactive neurons. The first histamine-immunoreactive neurons appeared in the ventral hypothalamus at about 85 h post-fertilization, and at 90 h, immunoreactive fibres terminated in the dorsal telencephalon. The embryonic histamine production described in mammals was lacking in this species. Both immunocytochemical and chromatographical studies indicated that histamine is absent in all other parts of the zebrafish body, and no specific hybridization was seen in any other part of the fish than the hypothalamus. The zebrafish could therefore be a very useful model for pharmacological in vivo studies of the histaminergic system of the brain, since the powerful peripheral actions of histamine should be lacking in this species.  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