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   1926篇
  免费   85篇
  国内免费   13篇
耳鼻咽喉   6篇
儿科学   17篇
妇产科学   74篇
基础医学   296篇
口腔科学   33篇
临床医学   141篇
内科学   653篇
皮肤病学   13篇
神经病学   72篇
特种医学   36篇
外科学   312篇
综合类   10篇
预防医学   28篇
眼科学   46篇
药学   77篇
中国医学   1篇
肿瘤学   209篇
  2023年   11篇
  2022年   17篇
  2021年   50篇
  2020年   13篇
  2019年   36篇
  2018年   35篇
  2017年   25篇
  2016年   39篇
  2015年   39篇
  2014年   56篇
  2013年   81篇
  2012年   125篇
  2011年   138篇
  2010年   73篇
  2009年   65篇
  2008年   127篇
  2007年   121篇
  2006年   122篇
  2005年   103篇
  2004年   111篇
  2003年   137篇
  2002年   96篇
  2001年   35篇
  2000年   24篇
  1999年   33篇
  1998年   20篇
  1997年   18篇
  1996年   15篇
  1995年   8篇
  1994年   18篇
  1993年   16篇
  1992年   24篇
  1991年   17篇
  1990年   19篇
  1989年   19篇
  1988年   16篇
  1987年   8篇
  1986年   10篇
  1985年   13篇
  1984年   9篇
  1983年   8篇
  1980年   7篇
  1979年   5篇
  1978年   7篇
  1975年   6篇
  1974年   4篇
  1973年   5篇
  1972年   5篇
  1971年   6篇
  1970年   8篇
排序方式: 共有2024条查询结果,搜索用时 15 毫秒
81.
Abstract:  HVOO may lead to graft dysfunction in LDLT. Balloon angioplasty is the first treatment for HVOO. However, some cases with recurrent HVOO need multiple interventions and require stent placement. The authors describe a pediatric case with recurrent HVOO requiring multiple stent placements. Her symptoms related to HVOO finally disappeared after the third stenting. A year later, follow-up liver biopsy did not show any dramatic change in perivenular fibrosis. From a review of our pediatric cases with HVOO requiring stent placement, the majority of them lost the grafts, because the timing of stent placement was too late to prevent the progression of fibrosis. In conclusion, stent placement should be considered in select cases of HVOO. Serial liver biopsies evaluating the degree of fibrosis are essential in determining the timing of stent placement.  相似文献   
82.
Indomethacin exerts a strong tocolytic effect by suppressing uterine contractions mediated by prostaglandins. However, indomethacin also induces in utero closure of fetal ductus arteriosus (DA), leading to serious neonatal consequences. Using rats, we tested the effect of an agonist for a subtype of prostaglandin E2 receptor (EP4), ONO-AE1-437 and its prodrug ONO-4819, as a DA dilator during indomethacin treatment. In vitro, ONO-AE1-437 exhibited a potent dilatory effect on DA against O(2)- and indomethacin-induced contractions in a concentration-dependent manner. In vivo, rat dams were given indomethacin (10 mg/kg, p.o.) alone or with ONO-4819 (0.3 micrograms/kg/h, s.c.) on d 21 of gestation and pups were delivered 4 h later through cesarean section to evaluate the ratio of diameter of DA to that of pulmonary artery. Pups from dams with no drug had DA/PA ratio of 0.9 +/- 0.05, whereas those from dams with indomethacin alone had a decreased ratio of 0.2 +/- 0.03. When ONO-4819 was co-administered to the dams, the ratio recovered significantly to 0.7 +/- 0.06. The administration of ONO-4819 to the dams did not induce any increase in the uterine activity. These results suggest that administration of an EP4 agonist in addition to indomethacin might prevent adverse reactions of indomethacin on fetal DA without restricting its tocolytic effects.  相似文献   
83.
Previously, we established the in vivo lung metastasis model of rat HCC induced by two hepatocarcinogens, diethylnitrosamine (DEN) and N-nitrosomorpholine (NMOR) at a dose of 120 ppm. This model allows us to investigate modifying factors leading to the inhibition of metastasis formation. However, low survival rates made the evaluation of metastasis formation difficult. The current experiments were conducted to modify the experimental protocol to improve survival and to establish a better animal metastasis model. Lower doses of NMOR (80 or 40 ppm in drinking water) were given to F344 rats for 14 weeks after DEN treatment. Survival rates in the 80 ppm group and in the 40 ppm group were 57% and 81%, respectively and these values were significantly higher than that in 120 ppm. Incidences of lung metastasis in the 40 ppm group steadily increased up to 67% by week 36 while that in the 80 ppm increased sharply up to 86% by week 24. Severity of lung metastases in the 40 ppm group at week 36 was mild compared with the 80 ppm group at week 24. In the second experiment, in order to characterize HCC development and lung metastasis in the 40 ppm group, rats given DEN and then followed with 40 ppm NMOR were killed sequentially. Development of HCC was observed at week 14 and reached 100% incidence at week 20. First lung metastatic lesions were evident at week 22, and incidence of lung metastasis reached 100%. Tumor cells were identified in the blood at week 20 by RT-PCR. The current study revealed that 40 ppm NMOR for 14 weeks after DEN treatment developed HCC without lung metastases at week 22, then HCC with a frequent lung metastasis at week 40. Thus, it can be said that this system is a more appropriate model for elucidation of mechanisms of metastasis and also for analysis of factors to inhibit natural metastasis.  相似文献   
84.
The long-term efficacy of lamivudine therapy in patients with hepatitis B virus (HBV) infection is still not clear. In this study, 20 non-cirrhotic Japanese patients infected with HBV received lamivudine therapy for more than 1 year and were followed for a median period of 8.5 years (range, 6.7-8.7 years). The rates of HBe antigen (HbeAg) negative, HBV-DNA undetectable, and alanine aminotransferase (ALT) normal level at the start of lamivudine were 55%, 25%, and 20% and 85%, 80%, and were 80%, respectively, at the last visit, including patients who received additional treatment. The values at the last visit tended to and were significantly higher than those at the start. The values improved at the last visit regardless of the emergence of YMDD motif mutant and continuation of lamivudine. YMDD mutant and biochemical relapse with mutant virus (breakthrough hepatitis) appeared in 65% and 45% during follow-up, respectively, but severe breakthrough hepatitis occurred in only 5%. Furthermore, 80% of patients who received additional treatment for breakthrough hepatitis, regardless of continuation of lamivudine, were ALT normal level at the last visit, in contrast to 25% untreated. HBsAg clearance occurred in two patients of the discontinuous lamivudine group with non-vertical transmission, who were relatively young. One was infected with HBV genotype C with breakthrough hepatitis and the other had no YMDD mutant and was infected with genotype D, a rare type in Japan. None developed cirrhosis or hepatocellular carcinoma (HCC) during follow-up. Our results suggest that long-term lamivudine therapy improves long-term prognosis, especially when additional treatment for breakthrough hepatitis is used.  相似文献   
85.
86.
The aim of this study is to demonstrate and review the detailed microsurgical anatomy of the abducens nerve and surrounding structures along its entire course and to provide its topographic measurements. Ten cadaveric heads were examined using ×3 to ×40 magnification after the arteries and veins were injected with colored silicone. Both sides of each cadaveric head were dissected using different skull base approaches to demonstrate the entire course of the abducens nerve from the pontomedullary sulcus to the lateral rectus muscle. The anatomy of the petroclival area and the cavernous sinus through which the abducens nerve passes are complex due to the high density of critically important neural and vascular structures. The abducens nerve has angulations and fixation points along its course that put the nerve at risk in many clinical situations. From a surgical viewpoint, the petrous tubercle of the petrous apex is an intraoperative landmark to avoid damage to the abducens nerve. The abducens nerve is quite different from the other nerves. No other cranial nerve has a long intradural path with angulations and fixations such as the abducens nerve in petroclival venous confluence. A precise knowledge of the relationship between the abducens nerve and surrounding structures has allowed neurosurgeon to approach the clivus, petroclival area, cavernous sinus, and superior orbital fissure without surgical complications. Clin. Anat. 25:1030–1042, 2012. © 2012 Wiley Periodicals, Inc.  相似文献   
87.

Objective

We analyzed a large number of stage I clear cell carcinoma of the ovary (CCC) patients to estimate the survival impact of the capsule status in stage I CCC patients, particularly in comparison with non-CCC patients.

Methods

Clinicopathologic data on 564 patients with stage I epithelial ovarian cancer (EOC) collected under the central pathological review system were subjected to uni- and multivariable analyses to evaluate the disease-free survival (DFS) and overall survival (OS).

Results

There was no significant difference in both the OS and DFS of CCC patients between IA and IC(ir) (intraoperative capsule rupture) {IA vs. IC(ir); OS: P = 0.1402, DFS: P = 0.2701}. In contrast, CCC patients at IC(non-ir) {IC excluding for IC(ir), such as preoperative capsule rupture, positive ascites/washing, and surface involvement} showed a poorer OS and DFS than those at IC(ir), or those at the corresponding stage in non-CCC. In multivariable analysis, the capsule status was an independent prognostic factor of a poor OS and DFS {OS: HR, 2.832; 95% CI 1.156-6.938; P = 0.023; DFS: HR, 4.327; 95% CI, 1.937-9.667; P = 0.0004)} {In contrast, non-CCC: N.S. (OS/DFS)}. Furthermore, in CCC patients, intraperitoneal recurrences were more frequently observed in IC(non-ir) CCC than IA or IC(ir) CCC (P = 0.0083) {In contrast, non-CCC: N.S.}.

Conclusion

This study suggests that CCC patients other than those with intraoperative capsule rupture show a considerable risk for mortality despite adjuvant chemotherapy.  相似文献   
88.
89.
Ovarian cancer cells disseminate by attachment to the peritoneal mesothelial cell surface of the abdominal cavity. We therefore investigated the influence of conditioned medium (CM) from human peritoneal tissues and mesothelial cells on the secretion of matrix metalloproteinases (MMPs) by ovarian cancer cells. The molecular weights of MMPs stimulating factors derived from human peritoneal tissues and mesothelial cells were estimated using microconcentrators with various cut-off membranes. Human peritoneal tissues were obtained from 12 surgical patients, and mesothelial cells were isolated from three peritoneal specimens. Exposure to CM from peritoneal tissue caused a concentration-dependent increase of the MMP-2 and MMP-9 bands in CM from NOM1 ovarian cancer cells, as shown by zymography. There was a significant difference in the increase of MMP-2 and MMP-9 (2.46-fold and 7.14-fold, respectively, at 0.4mg/ml protein; P < 0.005). CM from mesothelial cells also significantly increased the secretion of MMP-9 by NOM1 cells. The molecular size of possible MMP-9-stimulating factors secreted by peritoneal tissues and mesothelial cells was above M 100000. Further, CM of peritoneal tissues and mesothelial cells also induced the invasiveness of NOM1 cells. These findings suggest that mesothelial cells may secrete some factors which predominantly induce the MMP-9 production and increase invading cell numbers.  相似文献   
90.
This study was performed to investigate the heterogeneity of physiological and pharmacological properties in segments of the facial veins with special reference to selective brain cooling. Canine facial veins were isolated and the isometric tension of each segment was measured using the organ bath technique. Vessels in the segments of the facial veins that run opposite to the buccal cavity automatically produced myogenic tone and tended to show spontaneous contractions, but vessels in other segments did not. When no contractile agent was used for precontraction, noradrenaline and adrenaline produced dose-dependent relaxations in the former venous segments, but contractions in the latter ones. A Schild plot analysis for metoprolol against denopamine and for ICI118,551 against salbutamol showed that the venous segments running opposite the buccal cavity contained both beta(1)- and beta(2)-adrenoceptors, but the other venous segments contained only beta(2)-adrenoceptors. Electrical field stimulation-induced tetrodotoxin-sensitive relaxations in the former venous segments were diminished by pretreatment with metoprolol, but not with ICI118,551, indicating that the electrical stimulation-induced relaxation may be related to the activation of beta(1)-adrenoceptors in the venous smooth muscles. In conclusion, the heterogeneity of the functional properties, especially in the distribution of beta-adrenoceptors, in different segments of canine facial veins was observed in the present study, and autoregulatory mechanisms, humoral mechanisms, and neural mechanisms were suggested to affect cranial venous drainage.  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