全文获取类型
收费全文 | 49799篇 |
免费 | 1951篇 |
国内免费 | 756篇 |
专业分类
耳鼻咽喉 | 298篇 |
儿科学 | 2783篇 |
妇产科学 | 1137篇 |
基础医学 | 3246篇 |
口腔科学 | 665篇 |
临床医学 | 3710篇 |
内科学 | 12125篇 |
皮肤病学 | 541篇 |
神经病学 | 1982篇 |
特种医学 | 1111篇 |
外科学 | 6188篇 |
综合类 | 5454篇 |
一般理论 | 2篇 |
预防医学 | 8332篇 |
眼科学 | 818篇 |
药学 | 2051篇 |
14篇 | |
中国医学 | 1128篇 |
肿瘤学 | 921篇 |
出版年
2024年 | 54篇 |
2023年 | 582篇 |
2022年 | 1301篇 |
2021年 | 1802篇 |
2020年 | 1581篇 |
2019年 | 4384篇 |
2018年 | 3571篇 |
2017年 | 2002篇 |
2016年 | 1077篇 |
2015年 | 1133篇 |
2014年 | 2528篇 |
2013年 | 2385篇 |
2012年 | 2071篇 |
2011年 | 2266篇 |
2010年 | 1879篇 |
2009年 | 1574篇 |
2008年 | 1390篇 |
2007年 | 1325篇 |
2006年 | 1022篇 |
2005年 | 940篇 |
2004年 | 762篇 |
2003年 | 761篇 |
2002年 | 504篇 |
2001年 | 456篇 |
2000年 | 327篇 |
1999年 | 296篇 |
1998年 | 241篇 |
1997年 | 288篇 |
1996年 | 178篇 |
1995年 | 137篇 |
1994年 | 128篇 |
1993年 | 74篇 |
1992年 | 75篇 |
1991年 | 64篇 |
1990年 | 56篇 |
1989年 | 41篇 |
1987年 | 41篇 |
1985年 | 1042篇 |
1984年 | 1484篇 |
1983年 | 1104篇 |
1982年 | 1192篇 |
1981年 | 1159篇 |
1980年 | 1016篇 |
1979年 | 1107篇 |
1978年 | 1028篇 |
1977年 | 709篇 |
1976年 | 922篇 |
1975年 | 810篇 |
1974年 | 716篇 |
1973年 | 766篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
The pattern of polymorphism in the C-band-positive constitutive heterochromatin of chromosomes #1, #9, and #16 was studied in fibroblasts from 23 unrelated patients with adenomatosis of the colon and rectum and in peripheral lymphocytes from 78 control persons. The parameters of the heterochromatic regions analyzed were relative size, symmetry-asymmetry within homologous chromosome pairs, and frequency of inversions. The polyposis coli patients had a significantly higher frequency (p less than 0.05) of partial and total heterochromatin inversion on chromosome #9 than the control group (37.0% compared with 21.8%). In the other parameters studied, no significant differences were found between patients and controls. 相似文献
102.
Keratin proteins and carcinoembryonic antigen in synovial sarcomas: an immunohistochemical study of 24 cases 总被引:3,自引:0,他引:3
Twenty-four synovial sarcomas were examined for the presence of keratin proteins by an indirect immunoperoxidase method with paraffin-embedded tissues. Keratin proteins were identified in 16 of 24 cases (67 per cent). Both the pseudoglandular and spindle cell areas of all eight of the biphasic synovial sarcomas and the spindle cells of eight of the 16 monophasic synovial sarcomas contained keratin proteins. In spindle cell areas, staining was observed in single cells and small cords and clusters of cells in the absence of cleft formation or other evidence of a pseudoglandular component. The predominant cytologic staining pattern in all cases was peripheral, with localization of staining to the cell membrane or adjacent areas, but diffuse and focal cytoplasmic staining patterns were also observed. No staining for keratin proteins was seen in 101 control cases, including 52 sarcomas of various types. Carcinoembryonic antigen was also identified in four of the 24 synovial sarcomas by an indirect immunoperoxidase technique. The identification of keratin proteins may be helpful in the pathologic diagnosis of synovial sarcoma, particularly the spindle cell monophasic variant. 相似文献
103.
Bronchodilator efficacy of metaproterenol sulfate aerosol therapy delivered either by canister or jet nebulizer was compared in 25 patients, 13 with severe asthma and 12 with COPD. Treatment was carried out in double-blind crossover fashion on 2 days and consisted of either metaproterenol sulfate solution 15 mg in 2.3 ml administered from a jet nebulizer or three puffs of metered-dose metaproterenol sulfate (total 1.95 mg) inhaled sequentially. FVC and FEV1 were monitored before and after therapy for 2 hr. In 13 asthmatic patients, FEV1 increased from a baseline mean of 0.83 L to 1.57 L at 2 hr after jet nebulizer therapy and increased from 0.84 L to 1.52 L after canister therapy. In 12 patients with COPD, FEV1 increased from 0.58 L to 0.78 L after jet nebulizer therapy and from 0.57 L to 0.76 L after canister therapy. FVC also increased similarly after each form of therapy. The two types of aerosol therapy were equally effective and were without side effects. Canister therapy has the advantage over jet nebulizer therapy by being convenient and cheaper. 相似文献
104.
We present a patient with dysmyelopoietic syndrome and with a complex, hypotetraploid karyotype with numerous structural aberrations. 相似文献
105.
Michael Kaliner 《The Journal of allergy and clinical immunology》1976,58(2):308-315
The cholinergically innervated human eccrine sweat gland is a readily available organ permitting the assessment in allergic patients of cholinergic reactivity with few or no adrenergic influences. The sweat responses of four matched groups (male allergic, female allergic, male control, and female control) to intradermal Mecholyl from 0.1 μg to 100 μg was compared; the 45 male and 45 female allergic patients demonstrated statistically significant increases in sweat responses to essentially all concentrations of Mecholyl examined. No difference in the sweat responses of patients with allergic rhinitis alone as compared with patients with both allergic rhinitis and allergic asthma was noted. Five patients with intrinsic asthma most closely resembled the allergic groups in their responses and 8 patients with vasomotor rhinitis sweated at or below the control groups. The increased sensitivity of allergic patients to cholinergic stimulation as measured by eccrine sweat responses suggests that this hyperresponsiveness may be one of the underlying defects in allergic disease. 相似文献
106.
Trichosporon is a common cause of superficial mycotic infection but has rarely been associated with endocarditis. The case of a patient who had a peritoneovenous shunt for chronic intractable ascites due to Laennec liver cirrhosis is described. The shunt was revised on several occasions, and the last procedure was complicated by a draining skin sinus wound. To the authors' knowledge, this is the first reported case of Trichosporon endocarditis complicating a peritoneovenous shunt. 相似文献
107.
Masanori Hosokawa Ryuichi Kasai Keiichi Higuchi Shuji Takeshita Katsuji Shimizu Hajime Hamamoto Atsuko Honma Mika Irino Kayoko Toda Atsuko Matsumura Mutsumi Matsushita Toshio Takeda 《Mechanisms of ageing and development》1984,26(1):91-102
For evaluation of the degree of senescence in SAM-P, accelerated senescence prone mouse, formerly called SAM or prone series or P-series, consisting of SAM-P/1, SAM-P/2, SAM-P/3 and SAM-P/4 corresponding to P-1, P-2, P-3 and P-4 series, respectively, in the previous reports, and in SAM-R, accelerated senescence resistant mouse, formerly called resistant series or R-series, consisting of SAM-R/1, SAM-R/2 and SAM-R/3 corresponding to R-1, R-2 and R-3 series, respectively, in the previous reports, the grading score system was adopted. The items to be examined in this system include 11 categories selected from the clinical signs and gross lesions considered to be associated with the aging process. The degree of the senescence in each category was graded from 0 to 4 according to the detailed criteria devised in our laboratory. After 8 months of age each mouse was examined every 4 months, and some of the mice were examined after 2 months of age.In almost all categories, the grading score and incidence began to increase from 4 or 6 months of age and continued to increase with advancing age in both SAM-P and SAM-R. The increase, however, was more marked in SAM-P than in SAM-R. The slow but steady increase in the SAM-R levelled out at 24 months of age and was comparable to that of 12 months of age in SAM-P. In both SAM-P/1 at 8 months of age and SAM-R/2 at 12 months of age, there was a significant reverse correlation between total score of this grading score system and length of residual life after examination.Systematic and extensive studies using the grading score system showed that if the validity of the system is, based on “irreversibility” and “universality” of the changes in 相似文献
108.
M S Messina R Perry M Silverberg A P Kaplan G C Smaldone 《The Journal of allergy and clinical immunology》1985,76(4):605-609
To more nearly accurately quantitate the dose of pharmacologic agents delivered to human and animal airways via aerosols, we have developed a monodisperse aerosol containing either methacholine or histamine that permits a light scattering device (tyndallometry) to measure accurately the quantity of inspired and expired particles. These aerosols (described in previous studies) are simultaneously tagged with a radioactive label (technetium 99m) to permit the use of external gamma camera imaging. Present work focuses on the development of assay techniques to measure the quantity of methacholine delivered in these aerosols. The lack of specific radioimmune or radioenzyme assays coupled with the cross-reaction of organic contaminants with conventional chemical reagents for measuring methacholine required the development of separative techniques to isolate the methacholine from the organic aerosol contaminants. With aqueous extraction and column separation we have been able to completely isolate the methacholine from these contaminants. This allows the application of standard spectrophotometric assays for methacholine to quantitate the methacholine in the resulting solution. These separative techniques will permit the use of these aerosols in quantitative studies of airway reactivity. 相似文献
109.
Panettieri RA 《Respiratory physiology & neurobiology》2003,137(2-3):277-293
Although the pathogenesis of asthma remains unclear, substantial progress has been made over the past decades in the characterization of airway inflammation as a pathogenetic mechanism in asthma. New evidence suggests that airway smooth muscle (ASM), the most important cell modulating bronchomotor tone, plays an important immunomodulatory role in the orchestration and perpetuation of airway inflammation. Evidence now suggests that the signaling pathways that modulate leukocyte function may be disparate from those found in resident effector cells such as ASM, fibroblasts and epithelial cells. Further investigation and understanding of the critical signaling pathways that modulate ASM cell release, secretion of chemokines/cytokines and expression of cell adhesion molecules (CAMs) may offer new therapeutic approaches in the treatment of asthma. 相似文献
110.
Gary P. Zaloga Ulf R. Hierlwimmer Renata J. Engler 《The Journal of allergy and clinical immunology》1984,74(1):79-80
Psyllium is a hydrophilic agent found in many bulk laxative preparations. We report the occurrence of an anaphylactic reaction in a patient after ingestion of a psyllium-containing laxative. IgE mediation of the reaction was suggested by a positive immediate skin test to psyllium, positive passive transfer skin test, lack of skin response during passive transfer with heat treated serum, and an elevated IgE (RAST) to psyllium seed. 相似文献