全文获取类型
收费全文 | 211157篇 |
免费 | 14941篇 |
国内免费 | 4638篇 |
专业分类
耳鼻咽喉 | 2690篇 |
儿科学 | 3618篇 |
妇产科学 | 4149篇 |
基础医学 | 29561篇 |
口腔科学 | 4126篇 |
临床医学 | 21469篇 |
内科学 | 38325篇 |
皮肤病学 | 4795篇 |
神经病学 | 14689篇 |
特种医学 | 10222篇 |
外国民族医学 | 19篇 |
外科学 | 27123篇 |
综合类 | 11029篇 |
现状与发展 | 18篇 |
一般理论 | 84篇 |
预防医学 | 13100篇 |
眼科学 | 5534篇 |
药学 | 18940篇 |
51篇 | |
中国医学 | 4372篇 |
肿瘤学 | 16822篇 |
出版年
2023年 | 1715篇 |
2022年 | 4564篇 |
2021年 | 7269篇 |
2020年 | 4327篇 |
2019年 | 5187篇 |
2018年 | 6058篇 |
2017年 | 4769篇 |
2016年 | 5737篇 |
2015年 | 7914篇 |
2014年 | 9699篇 |
2013年 | 11055篇 |
2012年 | 16504篇 |
2011年 | 16460篇 |
2010年 | 10310篇 |
2009年 | 8425篇 |
2008年 | 12079篇 |
2007年 | 11948篇 |
2006年 | 10982篇 |
2005年 | 10543篇 |
2004年 | 8953篇 |
2003年 | 8126篇 |
2002年 | 7020篇 |
2001年 | 5660篇 |
2000年 | 5008篇 |
1999年 | 4194篇 |
1998年 | 1868篇 |
1997年 | 1538篇 |
1996年 | 1309篇 |
1995年 | 1288篇 |
1994年 | 1057篇 |
1993年 | 827篇 |
1992年 | 1843篇 |
1991年 | 1767篇 |
1990年 | 1520篇 |
1989年 | 1404篇 |
1988年 | 1268篇 |
1987年 | 1151篇 |
1986年 | 1128篇 |
1985年 | 942篇 |
1984年 | 684篇 |
1983年 | 584篇 |
1982年 | 424篇 |
1981年 | 393篇 |
1980年 | 353篇 |
1979年 | 533篇 |
1978年 | 411篇 |
1977年 | 394篇 |
1976年 | 348篇 |
1974年 | 366篇 |
1973年 | 340篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Administered to a total of 788 children from grade 5 (N = 133), 7 (N = 193), 9 (N = 151), 11 (N = 158), and 13 (N = 153) a modification of Ellis' 11 irrational beliefs questionnaire reformulated for use with younger children. Results showed a linear decrease of percent item endorsement from younger to older children on 8 of 11 irrational ideas. Analysis of variance on the mean number of irrational ideas endorsed showed significant differences between children. Results indicated that endorsing irrational beliefs is a function of age and provided construct validity for the instrument presented here. Research and counseling uses of the scale are discussed. 相似文献
992.
Yoon HJ Kim H Kim HL Lee SG Zheng SH Shin JH Lim CS Kim S Lee JS Lee DS Kim YS 《Clinical genetics》2002,62(2):128-134
In order to investigate the interdependent action of the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene and polymorphism in exon 11 (C1136-->T; Ala379Val) of the platelet-activating factor acetylhydrolase (PAF-AH) gene, which encodes a functional antagonist of PAF, on the progression of immunoglobulin A (IgA) nephropathy, we analysed both polymorphisms in patients with primary IgA nephropathy, who were followed-up for longer than 3 years. During the follow-up (87.3 +/- 50.0 months), the disease progressed in 38 of the 191 patients (19.9%). The D allele of the ACE gene in the absence of the T allele of the PAF-AH gene did not affect the prognosis [odds ratio (OR), 3.6; 95% confidence interval (CI), 0.8-16.4] and neither did the T allele in the absence of the D allele (OR, 3.0; 95% CI, 0.4-24.2). However, the presence of both was a significant prognostic factor (OR, 6.6; 95% CI, 1.4-31.3). After adjusting for other risk factors, the presence of both proved to be an independent risk factor (OR, 4.5; 95% CI, 1.6-12.7). These results suggest that the interdependent effects of ACE and PAF-AH polymorphisms on the progression of IgA nephropathy might be more important than the effect of the individual polymorphisms. 相似文献
993.
Fas (APO-1/CD95) ligand and Fas expression in renal cell carcinomas: correlation with the prognostic factors 总被引:3,自引:0,他引:3
Kim YS Kim KH Choi JA Lee JH Kim HK Won NH Kim I 《Archives of pathology & laboratory medicine》2000,124(5):687-693
BACKGROUND AND OBJECTIVE: Fas ligand (FasL, CD95L) is a type II transmembrane protein of the tumor necrosis factor family that induces cells to send an apoptotic signal to cells expressing Fas (CD95, APO-1). It has been shown that cancers have a dysregulated expression of Fas and FasL system, conferring a survival advantage. It is important to understand FasL and Fas expression in tumors, because the growth of cancer might be controlled by Fas-mediated apoptosis. METHODS: The expressions of FasL and Fas were studied by immunohistochemical analyses in 51 cases of renal cell carcinomas and the adjacent normal renal tissues, respectively. In addition, their expressions were compared with prognostic factors, such as tumor size, nuclear grade, TNM stage, and histologic types. RESULTS: In nonneoplastic renal tissues, FasL was expressed in all nephron segments, whereas Fas also expressed in all tubules, except for glomeruli. In renal cell carcinomas, FasL protein was detected in 50 (98.0%) of 51 cases, whereas Fas expressed in 38 (74.5%) of 51 cases. In fact, the immunostaining of Fas was less intense than that in the adjacent normal segments of all cases. The staining pattern showing both high expression of FasL and low expression of Fas was found in 36 (70.6%) (P = .04) of 51 cases, most of which were Fuhrman grade 2 or 3 tumors. However, the expression pattern did not correlate statistically with the tumor size, histologic type, or clinical stage. On the other hand, most grade 4 tumors displayed high expression of both FasL and Fas (P<.001). CONCLUSION: These data indicate that high expression of FasL and low expression of Fas protein in renal cell carcinomas may play a role in evading surveillance of the immune system. In addition, the FasL and Fas expressions appear to have a therapeutic implication for high-grade tumors rather than a prognostic one. 相似文献
994.
Fahao Zhang Juwon Lee Daren Wang Zhongyun Dong 《Journal of interferon & cytokine research》2006,26(2):108-118
The purpose of this study was to investigate the therapeutic potential of interferon-beta (IFN-beta) against tumors that resist its antiproliferative effects. Mouse fibrosarcoma cells (UV-2237m-P) and their counterparts, transfected with either IFN-beta cDNA (UV-2237m-IFN-beta) or its control vector (UV-2237m-neo), were used in the study. UV-2237m-IFN-beta cells, still expressing functional IFN receptors, were resistant to the antiproliferative effects of IFN-beta. UV-2237m-P and UV-2237m-neo cells produced progressive tumors in both nude and IFN receptor-null nude (IFNAR-/-nude) mice. In contrast, growth of UV-2237m-IFN-beta cells was significantly delayed in nude mice. UV-2237m-IFN-beta tumors from nude mice contained fewer microvessels, fewer proliferating cells, and more apoptotic cells than did UV-2237m-P and UV-2237m-neo tumors. They expressed high levels of inducible nitric oxide synthase (iNOS) and were densely infiltrated by macrophages. Incubation with macrophages from nude mice, but not those from IFNAR-/- nude mice or iNOS-null/nude mice, led to more significant killing of UV-2237m-IFN-beta cells than that of control cells, which was blocked by iNOS inhibitor N-methylarginine. Similarly, more UV-2237m-IFN-beta cells were killed when they were incubated with spleen lymphocytes from nude mice. These data indicate that IFN-beta can inhibit growth of IFN-beta-resistant tumors by T cell-independent host-mediated mechanisms, including the role of macrophages, natural killer (NK) cells, and iNOS activity. 相似文献
995.
Gifford R Batchelor MM Lee Y Gokulrangan G Meyerhoff ME Wilson GS 《Journal of biomedical materials research. Part A》2005,75(4):755-766
In vivo glucose sensor nitric oxide (NO) release is a means of mediating the inflammatory response that may cause sensor/tissue interactions and degraded sensor performance. The NO release (NOr) sensors were prepared by doping the outer polymeric membrane coating of previously reported needle-type electrochemical sensors with suitable lipophilic diazeniumdiolate species. The Clarke error grid correlation of sensor glycemia estimates versus blood glucose measured in Sprague-Dawley rats yielded 99.7% of the points for NOr sensors and 96.3% of points for the control within zones A and B (clinically acceptable) on Day 1, with a similar correlation for Day 3. Histological examination of the implant site demonstrated that the inflammatory response was significantly decreased for 100% of the NOr sensors at 24 h. The NOr sensors also showed a reduced run-in time of minutes versus hours for control sensors. NO evolution does increase protein nitration in tissue surrounding the sensor, which may be linked to the suppression of inflammation. This study further emphasizes the importance of NO as an electroactive species that can potentially interfere with glucose (peroxide) detection. The NOr sensor offers a viable option for in vivo glucose sensor development. 相似文献
996.
Macrophage activity was studied in rats infected with Trypanosoma lewisi in three protocol groups: one group was fed complete diet, a second group was given a vitamin B12-deficient diet, and a third group was fed a pair-fed control (calorically restricted) diet. Throughout the observational period, in animals fed complete and pairfed diets, marked increases in acid phosphatase levels in peritoneal macrophages were directly related to the degree of parasitemia. Acid phosphatase levels in rats deprived of vitamin B12 were approximately one third that of animals with an adequate supply of the vitamin. Irrespective of the diets, the infection with T lewisi also elicited increased macrophage phagocytosis of polystyrene latex particles and macrophage spreading. Both of these activities occurred at a much slower rate in the vitamin B12-deficient animals. 相似文献
997.
This report describes an 11 month old female baby with features of pentasomy X. A molecular and cytogenetic evaluation revealed that her karyotype was 49,XXXXX and her extra X chromosomes were of maternal origin. She has muscular hypotonia, mental retardation, a cleft palate, mild hydrocephalus as a result of dilatation of both lateral ventricles, hyperextensible elbow joints, proximal radioulnar synostosis, clinodactyly of the fifth finger, valgus of the feet, and small hands and feet. In addition, she has a persistent pupillary membrane and congenital chorioretinal atrophy. The pathogenesis of pentasomy X is not clear at present, but it is thought to be caused by successive maternal non-dysjunctions. 相似文献
998.
In this study we investigate the expression pattern of mucin genes in the human testis and evaluate the relationship between the expression of mucin genes and impaired spermatogenesis in the human testis. Thirty human testis tissues were collected from patients undergoing diagnostic testicular biopsy to investigate the cause of infertility. One part of the tissue underwent histological observation, and the other part of the tissue was subjected to semiquantitative RT-PCR of mucin genes, that is, mucin1, 2, 3, 4, and 9. The relative amount of mucin mRNAs was calculated by densitometry using glyceraldehydes-3-phosphate dehydrogenase (GAPDH) as an internal control. The samples were histologically diagnosed as either obstructive azoospermia with normal spermatogenesis (n = 13) or non-obstructive azoospermia with impaired spermatogenesis (n = 17). In the human testis with normal spermatogenesis, mRNA expression of mucin1, 9, 13 and GAPDH were found, but RT-PCR products of mucin 2, 3 and 4 were not detected. In the testis with impaired spermatogenesis, however, RT-PCR product of mucin1 was not found. There was no difference in the other mucin mRNA expression patterns between the testis with either normal or impaired spermatogenesis. To our knowledge, this study is the first that has detected the mRNA of mucin9 and 13 in human testis. This study also shows that mucin1 expression might be closely related to spermatogenesis. Our findings should be substantiated by more direct evidence, such as mucin protein expression and localization. 相似文献
999.
Histochemical, immunohistochemical and ultrastructural studies were performed on cases of hepatocellular carcinoma (HCC) with pale bodies (PB). HCC containing PBs was observed in 3 (5.5%) of 55 consecutively resected HCC cases. Histologically, a large number of hepatocytes displayed pale or eosinophilic staining of the cytoplasm, resulting in ground-glass appearance. They were aggregated in nodular pattern, or diffusely intermixed with other malignant hepatocytes. PBs were negative for periodic-acid Schiff and Masson's trichrome staining. The inclusions showed a strong positive reaction for fibrinogen and some of them were weakly positive for albumin but negative for hepatitis B surface antigen, hepatitis B core antigen, alpha-fetoprotein and alpha-1-antitrypsin. Ultrastructurally, PBs were membrane-bound and contained granular materials of moderate electron density, and were closely related to dilated rough endoplasmic reticulum. These findings support that PBs are secretory fibrinogen accumulated in cystic ER and that such intracellular accumulation possibly reflects a defective transport of fibrinogen. 相似文献
1000.
Byun BH Lee SW Bae SH Choi JY Kim DG Byun JY Park YM Park DH Kim BS 《Journal of Korean medical science》1999,14(1):97-101
Biliary complications after orthotopic liver transplants are a continuing cause of morbidity and mortality. Biliary stones and sludge are less well known complications of hepatic transplantation, although they have long been recognized. Recently we experienced two cases of biliary stones developed after liver transplantation. One 32-year-old male, who frequently admitted due to recurrent cholangitis, was treated with percutaneous transhepatic biliary drainage and choledochojejunostomy with cholecystectomy. The other 58-year-old male, who had stones in commone bile duct, was treated by endoscopic manipulation. They are in good condition without recurrent bile duct stones or its accompanying complications. Although stones and sludge are relatively infrequent after liver transplantation, surgical or interventional radiologic treatments are usually performed for treatment. 相似文献