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   34727篇
  免费   2739篇
  国内免费   423篇
耳鼻咽喉   361篇
儿科学   1025篇
妇产科学   610篇
基础医学   5015篇
口腔科学   522篇
临床医学   3303篇
内科学   7467篇
皮肤病学   768篇
神经病学   2613篇
特种医学   1299篇
外国民族医学   16篇
外科学   4230篇
综合类   1290篇
现状与发展   1篇
一般理论   3篇
预防医学   2735篇
眼科学   711篇
药学   2611篇
  6篇
中国医学   631篇
肿瘤学   2672篇
  2023年   282篇
  2022年   673篇
  2021年   1121篇
  2020年   699篇
  2019年   861篇
  2018年   1066篇
  2017年   765篇
  2016年   773篇
  2015年   922篇
  2014年   1176篇
  2013年   1526篇
  2012年   2229篇
  2011年   2231篇
  2010年   1366篇
  2009年   1135篇
  2008年   1640篇
  2007年   1688篇
  2006年   1609篇
  2005年   1508篇
  2004年   1346篇
  2003年   1276篇
  2002年   1215篇
  2001年   1119篇
  2000年   1106篇
  1999年   986篇
  1998年   343篇
  1997年   305篇
  1996年   263篇
  1995年   211篇
  1994年   210篇
  1993年   176篇
  1992年   517篇
  1991年   501篇
  1990年   476篇
  1989年   437篇
  1988年   453篇
  1987年   382篇
  1986年   372篇
  1985年   372篇
  1984年   258篇
  1983年   187篇
  1982年   119篇
  1981年   103篇
  1979年   211篇
  1978年   113篇
  1977年   125篇
  1976年   113篇
  1974年   130篇
  1972年   128篇
  1969年   104篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
We studied 54 patients who, after small intestinal resection, developed a massive protracted diarrhea with a daily fecal loss greater than 2 kg, status we defined as the "overwhelmed intestine syndrome" (OIS). Median length of residual small bowel was 120 cm, 19 patients had a definitive stoma (jejunostomy, n = 9; colostomy, n = 10), 26 patients had a provisional jejunostomy. Fecal weight greater than 2 kg was related to enteral hyperalimentation (greater than 3,500 Kcal) in 19 patients (induced OIS) and was clearly independent in 16 others who had fecal weight over 3 kg while receiving approximately 2,000 Kcal (obligatory OIS); the last 19 patients had fecal weight between 2 and 3 kg during normoalimentation. Hypocalcemia and hypomagnesemia were common in the three groups. The other complications were seen mostly in patients with obligatory OIS: in those patients, parenteral nutrition was maintained in 9 cases out of 16 (vs. 0 in other groups), nutritional gain was scanty, sodium equilibrium was difficult to obtain in spite of a large sodium intake (380 mmol/day), hospitalization lasted several months and autonomy via the enteral route could not be achieved in 7 out of the 9 patients with definitive short bowel (vs. 0 in other groups). This study shows that the OIS is an unique functional entity. Complications and prognosis are dependent on the obligatory or induced pattern of the syndrome. Only patients with obligatory OIS require definitive home parenteral nutrition.  相似文献   
53.
A retrospective study of 2498 patients who made multiple visits to a sexually transmitted disease clinic over a 13-year period analyzed risk factors, default patterns, and repeated infections associated with gonococcal urethritis. An analysis of visitation patterns found that being young, black, and male and having a history of gonococcal urethritis before visiting the clinic was positively related to the total time a patient remained involved with the clinic. Default rates for all patients increased with successive clinic visits. A focused analysis was carried out on the records of 146 patients who returned to the clinic within 12 months with a second diagnosis of gonococcal urethritis. It was found that this group of "repeaters," who comprised 15% of the total population with gonococcal urethritis, accounted for approximately 29% of all diagnoses of this infection over the 13-year study period. Repeaters were found to be more frequently male, black, single, and to be less likely to return for a test-of-cure culture. Longitudinal analysis found that the median time repeaters remained involved with the clinic was approximately 130 days. The relatively brief clinic "half-life" and rapid rates of removal of repeaters are discussed in terms of the development of strain-specific immunity to Neisseria gonorrhoeae in a closed population of patients.  相似文献   
54.
OX39, a murine IgG1 monoclonal antibody (MoAb) that recognizes the 55 kDa alpha chain of the rat interleukin 2 receptor (R-IL2), was studied in vitro for its ability to interfere with IL2 binding and IL2-induced proliferation on rat concanavalin A (ConA) blasts and in vivo in a model of rat heart allografts. In vitro studies indicated that OX39 MoAb interacts with a single class of sites on the alpha chain of the rat R-IL2 with a high affinity (KD=0.8 nm) and competes with IL2 binding on this chain (KI=0.53 nm). In contrast, OX39 MoAb was found to be 10–20 times less efficient in competing with IL2 binding to the high-affinity R-IL2 (KI10 nm). It is proposed that the epitope recognized by OX39 on the alpha chain (low-affinity R-IL2) is modified on (or buried in) the high-affinity R-IL2 configuration. Accordingly, OX39 was found to be a weak inhibitor in vitro on IL2-induced proliferation and in vivo on allograft rejection. Allograft survival was unaffected by doses of OX39 of 20 and 50 g/rat for 9 days; only a borderline effect was noted when doses as high as 250 g/rat were used. A significant, but restricted, effect of OX39 could be further detected when combined with low doses of cyclosporine A (1.5 mg/kg), which were ineffective by themselves. Together, our data suggest that in order to be efficient in vivo, anti-R-IL2 MoAbs must bind with high affinity to epitopes involved in the high-affinity IL2 binding site.  相似文献   
55.
Solitary plasmacytoma of the spine. Long-term clinical course   总被引:6,自引:0,他引:6  
The data for 19 patients with solitary plasmacytoma of the spine were reviewed with regard to clinical course and prognosis (median follow-up, 96 months). Eight patients presented with spinal cord compression. A monoclonal immunoglobulin was initially detected in seven of 15 evaluable patients. Treatment included radiotherapy (18 of 19) and/or surgery (11 of 19) and chemotherapy (eight of 19). Spinal cord compression was reversed in every patient. The expected survival rate was 85% at 10 years after diagnosis. Local recurrence or dissemination was observed in 13 patients. It occurred within 5 years of diagnosis in 11 patients and was localized (that is, local recurrence or single bone metastasis) in eight patients. It was always associated with the appearance or an increase of the M component. Dissemination frequently had a "metastatic" pattern with no diffuse bone marrow plasmacytosis. The incidence of local recurrence (five patients) and leukemia (four patients) was high. Local recurrence and/or dissemination were significantly more frequent in patients with the M component at diagnosis than in those without it (P less than 0.05; relative risk, R = 4). The effectiveness of surgery and chemotherapy combined with radiotherapy is also discussed.  相似文献   
56.
Spectrum of NSD1 mutations in Sotos and Weaver syndromes   总被引:8,自引:0,他引:8  
Interestingly, mental retardation was consistently more severe in patients with NSD1 deletions. Macrocephaly and facial gestalt but not overgrowth and advanced bone age were consistently observed in Sotos syndrome patients. We suggest therefore considering macrocephaly and facial gestalt as mandatory criteria for the diagnosis of Sotos syndrome and overgrowth and advanced bone age as minor criteria.  相似文献   
57.
Four affected siblings in a Costa Rican family presented an aggressive polyneuropathy with widespread involvement of many visceral organs and onset during the third decade of life with rapid loss of muscle mass in the lower limbs and severe dysautonomy. The medical histories include vitreous opacity, cardiac enlargement, dermal and gastrointestinal infiltration, and autonomic dysfunction including circulatory compromise and gastrointestinal disturbances. Histological studies using Congo red stain and immunohistochemical assays with antibodies against the transthyretin (TTR) protein showed widespread deposition of amyloid in extracellular areas, including dermis and gastrointestinal lamina propia, endo- and perineural spaces, and vascular walls. A mutation search in the transthyretin (ttr) gene was performed seeking the cause of this severe form of familial amyloidotic polyneuropathy (FAP). We applied single-stranded conformational polymorphism (SSCP)-analyses followed by sequencing of the four exons of the ttr gene, revealing a point mutation in exon 3, a G to A transition that causes a Glu54Lys codon change. Western blots of plasma proteins incubated with anti-transthyretin antibodies after gel electrophoresis provided separation of wild-type and mutant TTR protein in affected family members.  相似文献   
58.
59.
In this paper we chose to emphasize three aspects of our work. First we underlined that “low grade and high grade” D weak red blood cells studied at the DNA level could, when monoclonal antibodies were used, give patterns of positive and negative reactions like partial RH1(D) cells. Secondly, we showed the importance of the technical conditions of the study which are essential for establishing a pattern of reactivity defining an epitope. It appears that the use of papain treated cells at room temperature can be misleading for the definition of epitope especially with IgM antibodies. Lastly we pointed out the interest of Rh variant cells, defined at the gene level, to study the expression of RH1(D) epitopes on the external part of the membrane.  相似文献   
60.
Myocardial dysfunction without coronary involvement may occur in acute cerebral diseases. The inverted Takotsubo pattern has been recently recognized as a novel heart neurologic stress-related syndrome. We report on the case of a 40-year-old woman presenting with massive subarachnoid hemorrhage and brain death. Echocardiography revealed an extensive left ventricular circumferential akinesis except at the apex. Histologic analysis of the heart confirmed the absence of myocardial infarction and revealed only sparse foci of myocyte necrosis with contraction bands in the akinetic areas.  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