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   4691篇
  免费   270篇
  国内免费   35篇
耳鼻咽喉   78篇
儿科学   120篇
妇产科学   81篇
基础医学   520篇
口腔科学   39篇
临床医学   310篇
内科学   1225篇
皮肤病学   40篇
神经病学   378篇
特种医学   200篇
外科学   983篇
综合类   47篇
预防医学   217篇
眼科学   79篇
药学   296篇
中国医学   12篇
肿瘤学   371篇
  2023年   21篇
  2022年   81篇
  2021年   136篇
  2020年   70篇
  2019年   99篇
  2018年   139篇
  2017年   108篇
  2016年   117篇
  2015年   136篇
  2014年   173篇
  2013年   206篇
  2012年   301篇
  2011年   325篇
  2010年   182篇
  2009年   156篇
  2008年   231篇
  2007年   230篇
  2006年   230篇
  2005年   223篇
  2004年   210篇
  2003年   185篇
  2002年   161篇
  2001年   120篇
  2000年   113篇
  1999年   90篇
  1998年   33篇
  1997年   30篇
  1996年   29篇
  1995年   30篇
  1994年   20篇
  1992年   58篇
  1991年   48篇
  1990年   52篇
  1989年   42篇
  1988年   53篇
  1987年   50篇
  1986年   34篇
  1985年   48篇
  1984年   31篇
  1983年   34篇
  1982年   21篇
  1981年   20篇
  1979年   49篇
  1978年   31篇
  1977年   21篇
  1976年   22篇
  1975年   23篇
  1974年   29篇
  1973年   33篇
  1972年   24篇
排序方式: 共有4996条查询结果,搜索用时 0 毫秒
111.
Nematode worms of the genus Trichinella are one of the most widespread zoonotic pathogens. Natural transmission between hosts can only occur through the ingestion of infected meat. To date, two Trichinella species are known to be etiological agents of disease among domestic animals and wildlife in Poland: T. spiralis and T. britovi. In the last decades, since the administration of an oral vaccination against rabies, the red fox population in Poland has increased exponentially. The study area covers the Nowy Targ region: a mountainous area (585–1138 m above the sea) in southern Poland. Of 24 red foxes examined in the study, four were infected with Trichinella isolates: three were identified as T. britovi and one as T. pseudospiralis. The muscle of red foxes infected with T. britovi harboured 2.75, 3.11, 4.4 LPG and with T. pseudospiralis 0.36 LPG. Trichinella larvae were identified at species level by genomic and mitochondrial multiplex PCR, the products of which were sequenced for comparison with other sequences available in GenBank. The sequences obtained from the Polish T. pseudospiralis isolate, deposited in GenBank under the accession numbers JQ809660.1 and JQ809661.1, matched sequences already published in GenBank. Sequence comparison showed a 100% match with the large subunit ribosomal RNA gene of T. pseudospiralis isolate ISS 013, and a 96–95% match with those of T. pseudospiralis isolates ISS 141 and ISS 470. This is the first report of the identification of T. pseudospiralis larvae from red fox in Poland.  相似文献   
112.
Artificial pancreas systems control insulin-mediated glucose uptake. Although these systems are widely used in the clinical setting, they are still fraught with structural and biological problems. The non-insulin mediated glucose uptake (NIMGU) mechanism could be an alternative candidate as a target system for the artificial control of peripheral glucose uptake. Although the sympathetic nervous system is known to be one of the regulators of NIMGU, the effects of peripheral sympathetic activation on glucose uptake have not been well documented. We electrically stimulated a sympathetic nerve fascicle to clarify the possibility of controlling peripheral glucose uptake. A sympathetic signal was microneurographically obtained in the unilateral sciatic nerve in normal (NRML), insulin-resistant high-fat-fed (HFF), and streptozotocin-induced insulin-depleted (STZ) rats, and electrical stimulation was applied via the microelectrode (microstimulation). The microstimulation was also applied to sites other than the sympathetic fascicles in an additional group of normal rats (NSYMP group). The stimulation applied to the sympathetic fibers resulted in an immediate and transient decrease of blood glucose (BG) in the NRML, HFF, and STZ groups, with little change in the plasma insulin. The change in BG level seemed to depend on the basal BG level (NRML < HFF < STZ). In contrast, no reduction in BG was observed in the NSYMP group. These results suggest that microstimulation in the peripheral sympathetic fascicle could enhance glucose uptake in peripheral tissues—independently of insulin function—and show an alternative possibility for controlling glucose uptake.  相似文献   
113.
114.
115.
116.
We describe herein a case of unilateral pulmonary agenesis (PA) with oesophageal atresia (EA)/tracheoesophageal fistula (TEF) that was diagnosed prenatally and repaired by esophagoesophagostomy with stable postoperative course. The patient was born at 34 weeks gestation, after ultrasonography at 22 weeks gestation showed possible right-sided diaphragmatic eventration or PA and EA was subsequently suspected due to hydramnios. The initial X-ray showed mediastinal shift to the right, and coil up sign of the nasogastric tube, without intracardiac anomaly. Immediately after the diagnosis of EA/TEF and unilateral PA on day 0, the patient was intubated in the operating room, and a gastrostomy tube was placed. After pulmonary status stabilized, at 4 days old, EA/TEF was repaired through a thoracotomy in the right 4th intercostal space. The right main bronchus was noted to continue into the distal oesophagus; this fistula was ligated and divided, and a single-layer esophagoesophagostomy was performed under mild tension with one vertebral gap. The neonate was maintained on mechanical ventilation and gradually weaned to extubation at 7 days old. The postoperative course was uneventful, with the exception of prolonged jaundice that emerged at 3 months old. Laparoscopic cholangiography at that time excluded biliary atresia, and jaundice resolved spontaneously. The patient has not shown any respiratory symptoms or feeding difficulties as of the 12-month follow-up.  相似文献   
117.
Current techniques for the detection of recurrent coronary stenoses following bypass grafting have shown disappointing diagnostic accuracy. This study used the same dipyridamole-handgrip stress to compare the accuracy of rubidium-82 positron emission tomography and thallium-201 single photon emission computed tomography, in 50 consecutive post-bypass patients undergoing coronary arteriography at a mean interval of 6.5 years after surgery. Significant stenoses in native coronary vessels (greater than 50% diameter) or grafts (greater than 70% diameter) were defined by quantitative angiography. Forty-six patients had recurrent or residual stenoses, 43 (93%) had a perfusion defect identified by positron emission tomography, and 35 (76%) were identified by single photon emission computed tomography (P = 0.04). Fourteen of the 17 patients (82%) without previous Q-wave myocardial infarction were identified by positron emission tomography; 10 of the 17 (59%) were detected by single photon emission computed tomography (P = NS). Stress-induced perfusion defects were demonstrated by positron emission tomography in 19 patients; of this group, thallium imaging identified reversible defects in 11, showed no perfusion defect in 1, and portrayed a persistent defect in 7 patients. Significant graft disease was present in 33 patients; perfusion defects were identified by positron emission tomography in 30 (91%), and by single photon emission computed tomography in 24 (73%, P = NS). Four patients were fully revascularized, without significant recurrent coronary disease; normal perfusion was present in 3 (75%) by positron emission tomography, and 4 (100%) by single photon emission computed tomography.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
118.
Agonistic monoclonal antibodies to CD40 (CD40 mAbs) have a puzzling dual therapeutic effect in experimental animal models. CD40 mAbs induce tumor regression by potentiating antitumoral T-cell responses, yet they also have immunosuppressive activity in chronic autoimmune inflammatory processes. CD40 mAbs are thought to act on antigen presentation by dendritic cells (DCs) to T cells. DCs can be distinguished as either immature or mature by their phenotype and their ability to generate an effective T-cell response. Here we found that, on human cells, although anti-CD40 led immature DCs to mature and became immunogenic, it also reduced the capacity of lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-alpha)-matured DCs to generate a specific CD4 T-cell response. This inhibitory effect was related to rapid and selective apoptosis of mature DCs. Anti-CD40-mediated apoptosis was due to an indirect mechanism involving cooperation with the death domain-associated receptor Fas, leading to activation of Fas-associated death domain protein (FADD) and caspase-8. On human cells, CD40 activation by such agonists could, therefore, trigger immune responses to antigens presented by immature DCs, which are otherwise nonimmunogenic, by inducing maturation. On the other hand, anti-CD40 mAbs, by rapidly inducing apoptosis, may reduce the capacity of inflammatory signal-matured immunogenic DCs to generate an effective T-cell response. These results call for caution in CD40 mAb-based immunotherapy strategies.  相似文献   
119.

Background

In a statement by the second International Consensus Conference for Laparoscopic Liver Resection (LLR), minor LLR was confirmed to be a standard surgical practice, as it has become adopted by an increasing proportion of surgeons. However, it is unclear whether this applies to the more complex group of patients suffering from cirrhosis. Therefore, the aim of this retrospective study was to compare the feasibility and safety of LLR for hepatocellular carcinoma (HCC) between non-liver cirrhosis (NLC) patients and liver cirrhosis (LC) patients at a single high-volume laparoscopy center.

Methods

From the beginning of 2000 to the end of 2013, open liver resection (OLR) was performed in 99 HCC patients, and LLR was in 118. The HCC patients who underwent LLR were divided into NLC-LLR (n=60) and LC-LLR (n=58) groups, and we compare the short-term outcomes between them.

Results

There was no significant difference in the incidence of blood loss and transfusion requirements between the NLC-LLR group and the LC-LLR group, although wedge resection was mainly performed in the LC-LLR group. There was no significant difference in the complication rate between the two groups, and the remarkable finding was that there was a significantly lower incidence of postoperative ascites in the LC-LLR group than in the NLC-LLR group.

Conclusions

According to our experience, it appears that LLR for selected HCC patients with cirrhosis is a feasible and promising procedure that is associated with less blood loss and fewer postoperative complications, especially the incidence of postoperative ascites. Further investigations are clearly warranted.  相似文献   
120.
Expression of p53 and c-myc was investigated and compared with cell proliferative activity in a series of 40 hepatocellular carcinomas (HCC), by means of enhanced immunohistochemistry. p53 expression was demonstrated in 5 out of 40 HCC (12.5%) with the incidence increasing in proportion to the histological grading of malignancy: thus, 0% of well-differentiated, 6.9% of moderately differentiated and 33.3% of poorly differentiated lesions were positive. The proliferating-cell nuclear antigen (PCNA) labeling index also showed a statistically significant increase with this grading. Distribution patterns of PCNA-positive cell were divided into four types: scatter, marginal, mosaic and diffuse. Four HCC cases, predominantly of the poorly differentiated type, exhibited the diffuse pattern. Generally, p53 overexpression corresponded well with PCNA positivity. In contrast, there was no correlation between c-myc overexpression, found in 19 out of 40 HCC (47.5%), and histological grading of HCC or PCNA labeling index. The distribution pattern of c-myc-positive HCC cells was also different from that of PCNA and p53. Our results suggest that p53 overexpression closely relates to proliferation of HCC cells. Furthermore, there may be a consistent difference in regulatory mechanisms between p53 and c-myc expression in multistep hepatocarcinogenesis.  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