全文获取类型
收费全文 | 1337782篇 |
免费 | 96051篇 |
国内免费 | 2927篇 |
专业分类
耳鼻咽喉 | 19761篇 |
儿科学 | 40317篇 |
妇产科学 | 38700篇 |
基础医学 | 187706篇 |
口腔科学 | 39866篇 |
临床医学 | 113020篇 |
内科学 | 262995篇 |
皮肤病学 | 30279篇 |
神经病学 | 106776篇 |
特种医学 | 53745篇 |
外国民族医学 | 435篇 |
外科学 | 208871篇 |
综合类 | 31073篇 |
现状与发展 | 6篇 |
一般理论 | 438篇 |
预防医学 | 92238篇 |
眼科学 | 31531篇 |
药学 | 100259篇 |
4篇 | |
中国医学 | 2991篇 |
肿瘤学 | 75749篇 |
出版年
2018年 | 11811篇 |
2015年 | 11953篇 |
2014年 | 16793篇 |
2013年 | 25356篇 |
2012年 | 33200篇 |
2011年 | 35092篇 |
2010年 | 20859篇 |
2009年 | 20344篇 |
2008年 | 33798篇 |
2007年 | 36887篇 |
2006年 | 37461篇 |
2005年 | 36209篇 |
2004年 | 35291篇 |
2003年 | 34238篇 |
2002年 | 33749篇 |
2001年 | 63651篇 |
2000年 | 65355篇 |
1999年 | 55427篇 |
1998年 | 14686篇 |
1997年 | 13503篇 |
1996年 | 12968篇 |
1995年 | 12248篇 |
1994年 | 11484篇 |
1992年 | 42786篇 |
1991年 | 41307篇 |
1990年 | 40576篇 |
1989年 | 39569篇 |
1988年 | 36978篇 |
1987年 | 36426篇 |
1986年 | 34914篇 |
1985年 | 33113篇 |
1984年 | 24830篇 |
1983年 | 21069篇 |
1982年 | 12679篇 |
1981年 | 11580篇 |
1980年 | 10785篇 |
1979年 | 23936篇 |
1978年 | 17078篇 |
1977年 | 14850篇 |
1976年 | 13397篇 |
1975年 | 15272篇 |
1974年 | 18089篇 |
1973年 | 17569篇 |
1972年 | 16820篇 |
1971年 | 15723篇 |
1970年 | 14917篇 |
1969年 | 14356篇 |
1968年 | 13466篇 |
1967年 | 12021篇 |
1966年 | 11266篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
992.
Direct modulation by androgens of the response of human bone cells (SaOS-2) to human parathyroid hormone (PTH) and PTH-related protein 总被引:3,自引:0,他引:3
We have reported previously that 17 beta-estradiol (E2) inhibits selectively the cAMP response to human (h) PTH and PTH-related protein (hPTHrP), but not to vasoactive intestinal peptide, in human osteoblast-like cells (SaOS-2). We have now extended these studies to investigate the actions of androgens on hPTH-stimulated accumulation of cAMP, and on the roles of new protein synthesis and pertussis toxin (PTox) substrates in the actions of steroid hormones on SaOS-2 cells. Pretreatment with testosterone (T) or 5 alpha-dihydrotestosterone (5 alpha-DHT) for 4-12 h at concentrations of 10(-12) to 10(-8) M inhibited significantly the cAMP response to hPTH by up to 50-70% of control. Like E2, the actions of T and 5 alpha-DHT were selective for hPTH or hPTHrP; there was no inhibition of the stimulatory action of vasoactive intestinal peptide. Two related steroids, 5 beta-DHT and 17 alpha-epitestosterone, did not inhibit the action of hPTH. Pretreatment of cells with cycloheximide, under conditions which inhibited protein synthesis by greater than 90%, reduced the cAMP response to hPTH but did not block the further inhibitory actions of E2, T, or 5 alpha-DHT. Pretreamtent of cells with PTox (100 ng/ml) for 24 h, enhanced the accumulation of cAMP stimulated by hPTH consistent with an action of PTox on Gi; however, the inhibitory actions of E2, T, and 5 alpha-DHT on PTH-stimulated cAMP accumulation were not attenuated by PTox. We conclude that androgens, as well as estrogens, act directly on human bone cells to modulate selectively an early effect of hPTH. The inhibitory actions of these steroid hormones do not appear to depend on new protein synthesis and may not involve a functionally active PTox substrate, presumably Gi. 相似文献
993.
Breast preserving surgery or conservative surgery consists at present of a combination of a reduced operation--tumorectomy or wedge resection or subcutaneous mastectomy--with adequate radiotherapy whereby a doses of 40-50 Gy is used with or without an additional booster dose of 10 Gy. Recent studies of 5-year- and 10-year-survival rates after conservative management have been shown to be identical with radical operations (Rotter-Halsted, Patey-Auchincloss). In the Departments of Gynecology and Obstetrics of the Universities of Münster and Rostock the partial bilateral subcutaneous mastectomy with lymphadenectomy and irradiation is the preferred method of conservative management for breast cancer. Indications and technique are discussed. 相似文献
994.
The use of pelvic ultrasonography in the evaluation of adolescents with pelvic inflammatory disease 总被引:2,自引:0,他引:2
N Golden H Cohen G Gennari S Neuhoff 《American journal of diseases of children (1960)》1987,141(11):1235-1238
To evaluate the use of pelvic ultrasonography in the diagnosis and management of female adolescents with pelvic inflammatory disease (PID), sonograms of 60 patients with PID were compared with those of 40 age-matched controls. Sonograms were evaluated for adnexal volume, adnexal adherence, uterine size, and the presence of cul-de-sac fluid. Eleven (19.3%) of the 57 patients with PID, in whom adequate sonograms were obtained, had tubo-ovarian abscesses; in seven of these patients, the abscesses were diagnosed ultrasonographically before suspected clinically. Even in those patients without tubo-ovarian abscesses, the mean (+/- SD) adnexal volume in the PID group was significantly larger than that of the control group (11.0 +/- 6.8 cm3 vs 5.2 +/- 2.7 cm,3 respectively). Adnexal adherence, uterine size, and the presence of cul-de-sac fluid were not useful in differentiating patients with PID from normal controls. Pelvic ultrasonography can be a useful adjunct in the diagnosis and management of PID in adolescents and may, in some instances, provide diagnoses in the absence of clinical findings. 相似文献
995.
996.
997.
Heiko Sch?der Diane L Carlson Dennis H Kraus Hilda E Stambuk Mithat G?nen Yusuf E Erdi Henry W D Yeung Andrew G Huvos Jatin P Shah Steven M Larson Richard J Wong 《Journal of nuclear medicine》2006,47(5):755-762
(18)F-FDG PET has a high accuracy in staging head and neck cancer, but its role in patients with clinically and radiographically negative necks (N0) is less clear. In particular, the value of combined PET/CT has not been determined in this group of patients. METHODS: In a prospective study, 31 patients with oral cancer and no evidence of lymph node metastases by clinical examination or CT/MRI underwent (18)F-FDG PET/CT before elective neck dissection. PET/CT findings were recorded by neck side (left or right) and lymph node level. PET/CT findings were compared with histopathology of dissected nodes, which was the standard of reference. RESULTS: Elective neck dissections (26 unilateral, 5 bilateral; a total of 36 neck sides), involving 142 nodal levels, were performed. Only 13 of 765 dissected lymph nodes harbored metastases. Histopathology revealed nodal metastases in 9 of 36 neck sides and 9 of 142 nodal levels. PET was TP in 6 nodal levels (6 neck sides), false-negative in 3 levels (3 neck sides), true-negative in 127 levels (23 neck sides), and false-positive in 6 levels (4 neck sides). The 3 false-negative findings occurred in metastases smaller than 3 mm or because of inability to distinguish between primary tumor and adjacent metastasis. TP and false-positive nodes exhibited similar standardized uptakes (4.8 +/- 1.1 vs. 4.2 +/- 1.0; P = not significant). Sensitivity and specificity were 67% and 85% on the basis of neck sides and 67% and 95% on the basis of number of nodal levels, respectively. If a decision regarding the need for neck dissection had been based solely on PET/CT, 3 false-negative necks would have been undertreated, and 4 false-positive necks would have been overtreated. CONCLUSION: (18)F-FDG PET/CT can identify lymph node metastases in a segment of patients with oral cancer and N0 neck. A negative test can exclude metastatic deposits with high specificity. Despite reasonably high overall accuracy, however, the clinical application of PET/CT in the N0 neck may be limited by the combination of limited sensitivity for small metastatic deposits and a relatively high number of false-positive findings. The surgical management of the N0 neck should therefore not be based on PET/CT findings alone. 相似文献
998.
999.
Carlos Alberto Herrero de Morais Norberti Bernardineli Roberto B Garcia Marco A H Duarte Danilo M Z Guerisoli 《Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics》2006,102(3):417-421
OBJECTIVE: The aim of this study was to evaluate the biocompatibility of Portland cement with the addition of iodoform, compared to MTA (ProRoot). STUDY DESIGN: Eighteen Wistar albino rats were divided into 3 groups of 6 animals each. Polyethylene tubes were filled either with freshly mixed MTA or Portland cement mixed with iodoform (20% wt/wt) and implanted subcutaneously. An empty tube served as control. After 7, 30, or 60 days, the implants together with the surrounding tissues were removed in blocks. Sections were evaluated for the presence and thickness of a fibrous capsule, presence of granulation tissue, and the severity of inflammatory response. Data were submitted to nonparametric statistical analysis with individual comparisons between groups at a significance level of P < 0.05. RESULTS: There were no differences between inflammatory responses at 7 and 30 days. After 60 days from surgical removal, there was significantly more tissue reaction to the MTA and Portland cement compared to the control group. CONCLUSION: There were no significant differences regarding inflammatory responses between MTA and Portland cement with iodoform after 7, 30, or 60 days. After 60 days, the fibrous capsule around the Portland cement appeared more organized than tissue surrounding MTA implants. After 60 days, there was still a significantly increased tissue reaction to the 2 cements compared to the empty polyethylene tubes. 相似文献
1000.