全文获取类型
收费全文 | 19494篇 |
免费 | 1251篇 |
国内免费 | 99篇 |
专业分类
耳鼻咽喉 | 175篇 |
儿科学 | 562篇 |
妇产科学 | 390篇 |
基础医学 | 2195篇 |
口腔科学 | 348篇 |
临床医学 | 1588篇 |
内科学 | 4076篇 |
皮肤病学 | 252篇 |
神经病学 | 1041篇 |
特种医学 | 657篇 |
外科学 | 3383篇 |
综合类 | 770篇 |
一般理论 | 17篇 |
预防医学 | 1488篇 |
眼科学 | 510篇 |
药学 | 1884篇 |
中国医学 | 257篇 |
肿瘤学 | 1251篇 |
出版年
2023年 | 177篇 |
2022年 | 530篇 |
2021年 | 673篇 |
2020年 | 440篇 |
2019年 | 542篇 |
2018年 | 654篇 |
2017年 | 456篇 |
2016年 | 378篇 |
2015年 | 526篇 |
2014年 | 730篇 |
2013年 | 897篇 |
2012年 | 1324篇 |
2011年 | 1304篇 |
2010年 | 798篇 |
2009年 | 618篇 |
2008年 | 1012篇 |
2007年 | 1005篇 |
2006年 | 949篇 |
2005年 | 866篇 |
2004年 | 782篇 |
2003年 | 710篇 |
2002年 | 590篇 |
2001年 | 555篇 |
2000年 | 493篇 |
1999年 | 407篇 |
1998年 | 188篇 |
1997年 | 172篇 |
1996年 | 157篇 |
1995年 | 153篇 |
1994年 | 91篇 |
1993年 | 106篇 |
1992年 | 211篇 |
1991年 | 192篇 |
1990年 | 173篇 |
1989年 | 193篇 |
1988年 | 153篇 |
1987年 | 169篇 |
1986年 | 139篇 |
1985年 | 144篇 |
1984年 | 120篇 |
1983年 | 88篇 |
1982年 | 68篇 |
1981年 | 68篇 |
1980年 | 52篇 |
1979年 | 100篇 |
1978年 | 65篇 |
1977年 | 72篇 |
1976年 | 54篇 |
1975年 | 62篇 |
1973年 | 54篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
K E Dusenbery I H Alul E J Holland F M Khan S H Levitt 《International journal of radiation oncology, biology, physics》1992,24(2):315-320
Although postoperative beta irradiation for prevention of pterygium recurrence is widely used, its complication rate has not been widely appreciated. Thirty-six patients underwent pterygium excision followed by irradiation with 90Sr to between 1600 and 5300 cGy (median 2400) in two to four fractions over 7 to 27 days. A median of three fields were used in each treatment course (range two to 10). Most patients had undergone previous treatment for their pterygia, including surgery alone (25 patients), or both surgery and irradiation (5 patients). Overall, recurrences developed in 10 eyes (28%). Recurrence occurred in one eye after re-irradiation (20%), compared to 9 of 31 (29%) previously non-irradiated eyes (p greater than 0.1). There was no association with number of excisions and recurrences, although all but 6 patients had undergone more than one excision. Thirteen patients (36%) developed complications including: epithelial defect or corneal thinning (3), symblepharon (5), cataract (4) and corneal ulceration (1). Complications developed in 4 of the 5 (80%) re-irradiated eyes compared to 9 of 31 (29%) previously non-irradiated eyes (p less than 0.05). The power of the statistical analysis was limited by sample size, but no significant association was observed between the development of complications or recurrences and total dose, number of abutting fields, number of previous surgical excisions or patient age, even when re-irradiated patients were excluded. Recently described calibration uncertainties with the 90Sr applicator may explain in part these complications. Alternatively, technical factors such as the number of fields or volume treated may play a role. Excessive complications and recurrences with the use of postoperative beta irradiation in this series emphasize the danger of re-treatment and the need for alternative safe and effective therapies. 相似文献
12.
13.
W A Khan S S Park H V Gelboin D R Bickers H Mukhtar 《The Journal of investigative dermatology》1989,93(1):40-45
A single application of crude coal tar (CCT) solution (USP) to the skin of neonatal rats was shown to induce epidermal and hepatic cytochrome P-450(P-450)-dependent monooxygenase activities. To further characterize the induction response, in this study we have utilized highly specific monoclonal antibodies (MoAb) 1-7-1, 2-66-3, and 1-98-1 directed against highly purified rat liver P-450s induced by 3-methyl-cholanthrene, phenobarbital and ethanol, respectively. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of hepatic microsomes prepared from CCT-treated animals showed a significant increase in the coomassie blue stainable proteins in the P-450 region; however, this was not evident in epidermal microsomes. Immunoblot analysis of epidermal and hepatic microsomes with MoAb 1-7-1 revealed strong immunoprecipitin bands in both tissues. MoAb 2-66-3 showed significant immunoreactivity only with hepatic microsomes. Interestingly, CCT treatment resulted in suppression of immunoreactivity with MoAb 1-98-1 in hepatic microsomes. MoAb 1-7-1 and 2-66-3 exhibited concentration-dependent inhibitory effects in aryl hydrocarbon hydroxylase and 7-ethoxycoumarin-O-deethylase activities induced by CCT application. MoAb 1-7-1 was substantially more effective in this respect. Epidermal and hepatic microsomes prepared from CCT-treated rats showed significantly greater metabolism of benzo(a)pyrene (BP). MoAb 1-7-1 and MoAb 2-66-3 inhibited BP metabolism in both the tissues. However, MoAb 1-7-1 was more inhibitory in this regard as compared to MoAb 2-66-3. These studies indicate that topical application of therapeutic CCT to the skin of neonatal rats results in induction of P-450 isozyme c in epidermis and isozymes b and c in liver, and that this induction is associated with the suppression of P-450 isozyme j in liver. 相似文献
14.
Hodgkin's disease (HD) was diagnosed in 24 patients who were either seropositive for human immunodeficiency virus (HIV) (21) or members of a high-risk group (three), but had not developed acquired immune deficiency syndrome (AIDS). Clinical presentation of the disease was characterized by constitutional symptoms in all, especially fever (23/24) and disseminated disease (22/24) at diagnosis. Mediastinal adenopathy was rare. Bone marrow involvement was particularly frequent (12/24), and a positive bone marrow biopsy preceded lymph node biopsy in 5 of the 12. Histopathologic features of these tumors included an increased number of nonlymphoid stromal cells, i.e., histiocytic and/or fibroblastoid. In some tumors these fibrohistiocytoid stromal cells were arranged in bundles, but distinct nodule with birefringent collagen band formation was not observed. Twenty-two patients were treated, most with combination chemotherapy; one was untreated; one, unknown. Sixteen, including the one untreated, died with disease at 3 to 25 months; one died of an unrelated cause; four were alive at 3 to 24 months; three were lost to follow-up. Frequent bone marrow involvement at presentation suggests the usefulness of the bone marrow biopsy for diagnosis in subjects at risk, especially when they present with spiking fever of unknown origin. Contrary to most previous series, virtually all of our cases were of mixed cellularity type, characterized by increased fibrohistiocytoid stromal cells in place of depleting lymphocytes. The classic nodular sclerosing feature with birefringent collagen band formation was not observed. In conclusion, HIV-associated HD was characterized by advanced stage with fever at presentation, preponderance of mixed cellularity histologic type with increased fibrohistiocytoid stromal cells, and poor outcome. Hodgkin's disease in AIDS patients presents an intriguing biological model to study the role of stromal histiocytes in immunodeficient patients. 相似文献
15.
S R Cunningham G W Dalzell P McGirr M M Khan 《British medical journal (Clinical research ed.)》1987,294(6574):739-740
16.
Delineating the sites and progression of in vivo atrophy in multiple system atrophy using fluid-registered MRI. 总被引:1,自引:0,他引:1
Jonathan M Schott Jessica E Simon Nick C Fox Andrew P King M Nadeem Khan Lisa Cipolotti Dominic C Paviour John M Stevens Martin N Rossor 《Movement disorders》2003,18(8):955-958
We describe the pattern and progression of atrophy delineated using fluid registration of serial magnetic resonance imaging scans in a case of multiple system atrophy (MSA). The in vivo findings were consistent with those found at postmortem, including significant supratentorial atrophy concurrent with an unusual degree of cognitive impairment for MSA. 相似文献
17.
18.
19.
Dr. Seema A. Khan MD Nick J. Gonchoroff DrPH Linda E. Miller PhD 《Annals of surgical oncology》1997,4(6):462-469
Background: Many studies have addressed the effect of the timing of surgery for breast cancer relative to menstrual cycle phase, with
conflicting results. Explanations for the possibility that survival could be altered by the appropriate timing of breast cancer
surgery in humans remain speculative.
Methods: We examined the expression of three estrogen related proteins (c-erbB-2, cathepsin D, pS2) in the breast tumors from 69 premenopausal women sampled in different phases of the menstrual cycle.
Data on S-phase fraction and hormone receptor expression were also analyzed. Immunohistochemical assays were used to measure
the proteins of interest. S-phase fraction was determined by flow cytometry. Analyses were performed based on fraction of
cells staining positive for the protein, density of stain, and a histoscore that combined both fraction of positive cells
and density.
Results: We found no differences in c-erbB-2, cathepsin D, hormone receptor, or S-phase levels in tumors sampled in the follicular versus luteal phase, or perimenstrual
versus periovulatory phase. The exception was pS2, which was expressed at greater levels during the luteal than during the
follicular phase of the cycle (p<0.01); but there was no difference in pS2 expression when the patients were classified as
periovulatory versus perimenstrual.
Conclusions: Our findings do not support a variation in c-erbB-2, cathepsin D, S-phase fraction, or receptor expression as an explanation for the differences in breast cancer prognosis
when surgery is timed by menstrual cycle phase. The finding that pS2 (an indicator of hormone sensitivity, and possibly better
prognosis) is expressed at higher levels in tumor samples during the luteal phase suggests that the biologic profile of breast
tumors may vary with the menstrual cycle and that these variations deserve further study. 相似文献
20.