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   34468篇
  免费   1671篇
  国内免费   140篇
耳鼻咽喉   264篇
儿科学   511篇
妇产科学   418篇
基础医学   4592篇
口腔科学   1043篇
临床医学   2372篇
内科学   8720篇
皮肤病学   749篇
神经病学   2512篇
特种医学   1294篇
外科学   5585篇
综合类   131篇
一般理论   1篇
预防医学   1188篇
眼科学   633篇
药学   2366篇
中国医学   66篇
肿瘤学   3834篇
  2022年   228篇
  2021年   623篇
  2020年   291篇
  2019年   421篇
  2018年   567篇
  2017年   449篇
  2016年   541篇
  2015年   544篇
  2014年   746篇
  2013年   923篇
  2012年   1452篇
  2011年   1632篇
  2010年   849篇
  2009年   819篇
  2008年   1423篇
  2007年   1564篇
  2006年   1617篇
  2005年   1593篇
  2004年   1484篇
  2003年   1581篇
  2002年   1614篇
  2001年   1448篇
  2000年   1454篇
  1999年   1258篇
  1998年   473篇
  1997年   353篇
  1996年   318篇
  1995年   275篇
  1994年   245篇
  1993年   235篇
  1992年   913篇
  1991年   810篇
  1990年   736篇
  1989年   750篇
  1988年   677篇
  1987年   692篇
  1986年   603篇
  1985年   573篇
  1984年   368篇
  1983年   307篇
  1982年   161篇
  1979年   242篇
  1978年   181篇
  1977年   152篇
  1975年   153篇
  1974年   156篇
  1973年   169篇
  1970年   152篇
  1969年   154篇
  1967年   155篇
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
131.
132.
A Ikoma  N Nakamura  T Miyazaki  M Maeda 《Surgery》1992,111(5):595-600
We report a 64-year-old woman with double cancer of the gallbladder and the common bile duct associated with anomalous junction of the pancreaticobiliary ductal system. Eleven previous cases have been reported to date. From analysis of the 12 cases reviewed, including our patient, double cancer of the gallbladder and the common bile duct accompanied by anomalous junction of the pancreaticobiliary ductal system is characterized by the predominance of well-differentiated and superficial cancer.  相似文献   
133.
Leiomyoblastoma has been regarded as a neoplasm of smooth muscle origin. With recent progress in immunohistostaining techniques, many clinicopathological discrepancies have been pointed out about the origin of leiomyoblastoma. It has been claimed that gastrointestinal non-epithelial tumors should be regarded as stromal tumors in order to study their origin. In the present study, we performed various forms of immunohistostaining in seven cases of leiomyoblastoma to determine their origin. One case expressed desmine and muscle specific actin and was considered to be derived from smooth muscle. Four neoplasms expressed X-100 protein (two cases were also NSE positive) and were thought to be derived from the nerve. Two cases were of unknown derivation. These results suggest that the cells of leiomyoblastoma may arise from a primitive to totipotential cell of neural lineages that may anomalously express smooth muscle filaments.  相似文献   
134.
Patients with stage T3N0~2M0 gastric carcinoma (n = 108) were studied for relevant prognostic factors. Peritoneal lavage cytology (PLC) was performed in all. In univariate analysis, 5-year survival rates were better with smaller serosal invasion (diameter <3.0 cm vs. ≥3.0 cm, 61% vs. 37%, P < 0.05) and fewer metastatic nodes (≤5 vs. ≥6, 57% vs. 29%, P < 0.05). In multivariate analyses, only these two factors were significant. The predictive value of PLC was not shown in both univariate and multivariate analyses. Peritoneal recurrence occured in 14 (22%) of 77 patients with negative PLC, and in 3 (18%) of 17 with positive PLC, the difference being not significant. Our results indicate that PLC is insensitive in predicting the development of peritoneal recurrence. Its role in the estimation of survival is limited, as many will die of visceral or locoregional recurrence if not of peritoneal dissemination.  相似文献   
135.
Endoscopic resection has been accepted as the standard treatment for intramucosal gastric tumors of differentiated type. However, the indication was limited to small tumors to achieve en bloc resection and prevent local recurrence in cases of conventional endoscopic mucosal resection (EMR) such as the strip biopsy and the cap technique. To avoid multi‐fragmental resection, we have developed endoscopic submucosal dissection (ESD) as a new endoscopic resection technique. ESD is a remarkable technique, because we make it possible to remove the lesions en bloc regardless of size, shape, coexisting ulcer, and location. However, it is difficult or impossible to resect recurrent tumors en bloc in conventional EMR owing to hard fibrosis, and some patients need laparotomy. Using ESD, we can dissect the submucosal layer as we directly look at the submucosa, and remove the lesion safely and reliably even in cases of hard fibrosis. The key to treatment of recurrent tumors in ESD are as follows: (i) using enough submucosal injection solution (we use a mixture of Glyceol and 1% 1900 kDa hyaluronic acid preparation); (ii) incising the mucosa without fibrosis; (iii) understanding characteristics of various cutting devices, and changing other devices in difficult situations. In these ways we can remove the majority of the recurrent tumors en bloc. Hence, we consider that ESD is a very effective treatment which achieves excellent en bloc and complete resection rates and enables patients with intramucosal gastric tumors to a recurrent‐free survival even in recurrent tumors.  相似文献   
136.
137.
The effects of simultaneous increases in dietary phosphorus (P) and magnesium (Mg) concentrations while maintaining a constant P:Mg ratio on nephrocalcinosis and kidney function in female rats was investigated. Female Wistar rats were fed a control diet (3.12 g P, 0.51 g Mg per kg diet) or a diet having either 3 times the control P and Mg concentrations (3-fold diet; 9.25 g P and 1.42 g Mg per kg diet) or 5 times the control concentrations (5-fold diet; 14.97 g P and 2.37 g Mg per kg diet) for 21 d. The three experimental diets all had same P:Mg molar ratios (control diet; 4.81, 3-fold diet; 5.11, 5-fold diet; 4.96). The 3-fold diet had no significant influence on kidney calcium (Ca), Mg or P concentrations. However, kidney Ca, Mg and P concentrations were significantly higher in rats fed the 5-fold diet than in rats fed the control or 3-fold diets. No significant differences in creatinine clearance were observed among the three groups. Urinary albumin and beta 2-microglobulin excretion were higher in rats fed the 5-fold diet than in rats fed the control or 3-fold diets, while the 3-fold diet had no significant influence on the urinary albumin and beta 2-microglobulin excretion. These results suggest that absolute concentrations of dietary P and Mg are important factors with regard to the development of nephrocalcinosis and diminished kidney function.  相似文献   
138.
Liver transplantation, which serves as treatment of familial amyloidotic polyneuropathy (FAP), and domino liver transplantation, which utilizes resected livers from patients with FAP for treatment of liver diseases, may induce changes in transthyretin (TTR), a pathogenic FAP-related protein. To evaluate this possibility, we performed a 70% hepatectomy or administered tacrolimus to Dark Agouti (DA) rats for 7 days and then measured changes in liver TTR mRNA levels and changes in serum TTR concentrations. After hepatectomy, TTR mRNA levels decreased by 77%; at day 3, they returned to preoperative levels. Except for slightly elevated serum TTR concentrations 12 h after operation, serum TTR levels remained unchanged. Thus, partial hepatectomy did not influence serum TTR concentrations. After tacrolimus administration, TTR mRNA declined by 56% 12 h after the experiment started; however, after day 3, a rebound phenomenon occurred until day 7. Tacrolimus may facilitate serum TTR degradation, although production of TTR in the liver also increased. This finding -- that TTR, the source of FAP-inducing amyloid, did not increase after transplantation -- may help post-transplantation treatment of patients who have FAP and other liver diseases.  相似文献   
139.
The aim of this study was to elucidate the vasodilator mechanisms of barbiturates. In helical strips of dog mesenteric artery, the effects of pretreatment with thiopentone and pentobarbitone on the contractions induced by KCl (2.0 x 10(-2) M) and norepinephrine (10(-5) M) in normal bathing fluid, and those induced by norepinephrine and caffeine (2.5 x 10(-2) M) in Ca(++)-free fluid were tested, and their effects on caffeine-induced contractions in skinned strips were also examined. Thiopentone, at concentrations over 10(-4) M, inhibited the KCl-induced contractions in normal bathing fluid and those induced by caffeine in Ca(++)-free fluid and, at concentrations over 3 x 10(-4) M, inhibited norepinephrine-induced contractions in normal and Ca(++)-free bathing fluids significantly. Pentobarbitone, at concentrations over 3 x 10(-4) M, inhibited KCl- and norepinephrine-induced contractions in normal bathing fluid significantly, whereas contractions in Ca(++)-free fluid induced by norepinephrine and caffeine were inhibited only by a high concentration (10(-3) M) of pentobarbitone. Caffeine-induced contractions of chemically skinned fibres were more susceptible to inhibition by thiopentone than by pentobarbitone. These results suggest that the vasodilator effect of thiopentone is mediated via its intracellular inhibitory effect and that, in contrast, the vasodilator effect of pentobarbitone can be attributed mainly to its Ca(++)-channel blocking action.  相似文献   
140.
In order to clarify the involvement of cerebral 3,4-dihydroxyphenylacetic acid (DOPAC) and vasoactive intestinal polypeptide (VIP) in whole-body vibration stress, DOPAC and VIP-like immunoreactivity (VIP-LI) in various discrete brain regions of rats exposed to whole-body vibration (4G, 20 Hz, 90 min) were assayed. The results showed that the whole-body vibration increased the DOPAC level in the frontal cortex and nucleus accumbens, but did not induce a concurrent change of VIP-LI in these regions. VIP-LI was significantly increased in the amygdala, and decreased in the hippocampus, accompanied by no significant change of DOPAC. These results show that whole-body vibration affects cerebral VIP neuron systems in addition to its nonspecific action, i.e. the activation of mesofrontal and mesoaccumbens dopamine neuron systems. It is assumed that the amygdalofugal VIP neuronal system is involved in the regulation of hypothalamic and pituitary hormone secretions, and that VIP in the hippocampus plays a part in modulating the blood circulation in the cortex in whole-body vibration stress.  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