全文获取类型
收费全文 | 1391273篇 |
免费 | 91232篇 |
国内免费 | 3426篇 |
专业分类
耳鼻咽喉 | 16657篇 |
儿科学 | 46662篇 |
妇产科学 | 35784篇 |
基础医学 | 191783篇 |
口腔科学 | 33282篇 |
临床医学 | 124032篇 |
内科学 | 269494篇 |
皮肤病学 | 26586篇 |
神经病学 | 117192篇 |
特种医学 | 56514篇 |
外国民族医学 | 318篇 |
外科学 | 213921篇 |
综合类 | 28691篇 |
现状与发展 | 1篇 |
一般理论 | 553篇 |
预防医学 | 110758篇 |
眼科学 | 30346篇 |
药学 | 95921篇 |
4篇 | |
中国医学 | 2944篇 |
肿瘤学 | 84488篇 |
出版年
2021年 | 11571篇 |
2019年 | 11814篇 |
2018年 | 37951篇 |
2017年 | 29755篇 |
2016年 | 34224篇 |
2015年 | 16591篇 |
2014年 | 22623篇 |
2013年 | 32901篇 |
2012年 | 51091篇 |
2011年 | 67854篇 |
2010年 | 46007篇 |
2009年 | 37404篇 |
2008年 | 63347篇 |
2007年 | 69162篇 |
2006年 | 46103篇 |
2005年 | 46882篇 |
2004年 | 46776篇 |
2003年 | 46198篇 |
2002年 | 42447篇 |
2001年 | 49095篇 |
2000年 | 50011篇 |
1999年 | 42331篇 |
1998年 | 13940篇 |
1997年 | 12421篇 |
1996年 | 12045篇 |
1995年 | 11518篇 |
1994年 | 10668篇 |
1993年 | 9987篇 |
1992年 | 33243篇 |
1991年 | 32451篇 |
1990年 | 31888篇 |
1989年 | 30663篇 |
1988年 | 27884篇 |
1987年 | 28006篇 |
1986年 | 26114篇 |
1985年 | 25310篇 |
1984年 | 19276篇 |
1983年 | 16299篇 |
1982年 | 10317篇 |
1981年 | 9266篇 |
1979年 | 17381篇 |
1978年 | 12744篇 |
1977年 | 10742篇 |
1976年 | 10208篇 |
1975年 | 10474篇 |
1974年 | 12635篇 |
1973年 | 12088篇 |
1972年 | 11039篇 |
1971年 | 10259篇 |
1970年 | 9510篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
931.
Inorganic sling materials when used for treatment of urinary stress incontinence have a high success rate of achieving continence. They unfortunately attract the complication of vaginal tape erosion. When used for Transobturator tape procedure (TOT) we found the Obtape sling (Mentor-Porges, Le Plessis-Robinson, France) attracted a high rate of erosion, likely due to the tape properties. We describe a series of tape erosions with the Obtape sling, the presentation, conservative and surgical management with favourable rates of maintenance of continence. We suggest the use of larger pore sized tapes to decrease the occurrence of vaginal tape erosion. 相似文献
932.
Immune modulation by cadmium and lead in the acute reporter antigen-popliteal lymph node assay. 总被引:2,自引:0,他引:2
Immune modulation by heavy metals may cause serious adverse health effects in humans, although the mechanisms involved are not well understood. Both cadmium and lead are important environmental and occupational toxins. Therefore, in the current study, the costimulatory/adjuvant effects and the T-cell-activating potential of these metals (i.e., CdCl2 and PbCl2), are examined. These immune-modulating properties are critical in the development of conditions such as allergy, hypersensitivity, and autoimmunity. Using the direct popliteal lymph node assay (PLNA) and reporter antigen-popliteal lymph node assay (RA-PLNA) both metals were examined individually for immunotoxicity. Mercury (i.e., HgCl2) was included for comparative purposes as its effects in the RA-PLNA are well documented. Seven days following a single footpad injection containing metal and/or RA (trinitrophenyl-ovalbumin [TNP-OVA] or TNP-Ficoll), BALB/c mice were sacrificed and the popliteal lymph nodes (PLNs) removed. PLN cellularity, TNP-specific antibody-secreting cells (ASCs), and lymphocyte subsets were assessed. All three metals strongly stimulated T- and B-cell proliferation and ASC production following coinjection with the RA TNP-OVA. In each case, ASC production was skewed towards the IgG1 isotype. In addition, all three metals induced IgG production to TNP-Ficoll (although relatively weakly in the case of Cd). These results show that each of these metals can provide adjuvant signals to promote lymphocyte proliferation and enhance adaptive immune responses to unrelated antigens. Skewing of immune responses towards T helper type 2 responses suggests that each of these metals can enhance allergic and hypersensitivity reactions to environmental antigens. Furthermore, the induction of IgG responses to TNP-Ficoll, a T-cell-independent antigen, indicates that each of these metals can activate neoantigen-specific T cells. T-cell activation by metals can lead to metal hypersensitivity and has been implicated in the development of autoimmunity. This is the first report of immune modulation by CdCl2 and PbCl2 in the RA-PLNA. 相似文献
933.
Michael R Horsman 《International journal of hyperthermia》2006,22(3):197-203
The most important physiological parameter influencing tissue response to heat is blood flow. At mild hyperthermia temperatures blood perfusion increases in many tumours and this effect is heating time-, temperature- and tumour-dependent. These flow increases can improve tumour oxygenation. When heating is terminated, perfusion and oxygenation commonly recover, although how quickly this occurs appears to be tumour-specific. While these effects are unlikely to have any anti-tumour activity they can be exploited to improve the combination of heat with other therapies. However, since similar physiological effects should occur in normal tissues, such combination therapies must be carefully applied. Heating tumours to higher temperatures typically causes a transient increase in perfusion during heating, followed by vascular collapse which if sufficient will increase tumour necrosis. The speed and degree of vascular collapse is dependent on heating time, temperature and tumour model used. Such vascular collapse generally occurs at temperatures that cause a substantial blood flow increase in certain normal tissues, thus preferential anti-tumour effects can be achieved. The tumour vascular supply can also be exploited to improve the response to heat. Decreasing blood flow, using transient physiological modifiers or longer acting vascular disrupting agents prior to the initiation of heating, can both increase the accumulation of physical heat in the tumour, as well as increase heat sensitivity by changing the tumour micro-environmental parameters, primarily an increase in tumour acidity. Such changes are generally not seen in normal tissues, thus resulting in a therapeutic benefit. 相似文献
934.
C. J. M. Antens M. Oldenwening A. Wolse U. Gehring H. A. Smit R. C. Aalberse M. Kerkhof J. Gerritsen J. C. de Jongste B. Brunekreef 《Clinical and experimental allergy》2006,36(12):1525-1531
BACKGROUND: Studies of the association between indoor allergen exposure and the development of allergic diseases have often measured allergen exposure at one point in time. OBJECTIVE: We investigated the variability of house dust mite (Der p 1, Der f 1) and cat (Fel d 1) allergen in Dutch homes over a period of 8 years. METHODS: Data were obtained in the Dutch PIAMA birth cohort study. Dust from the child's mattress, the parents' mattress and the living room floor was collected at four points in time, when the child was 3 months, 4, 6 and 8 years old. Dust samples were analysed for Der p 1, Der f 1 and Fel d 1 by sandwich enzyme immuno assay. RESULTS: Mite allergen concentrations for the child's mattress, the parents' mattress and the living room floor were moderately correlated between time-points. Agreement was better for cat allergen. For Der p 1 and Der f 1 on the child's mattress, the within-home variance was close to or smaller than the between-home variance in most cases. For Fel d 1, the within-home variance was almost always smaller than the between-home variance. Results were similar for allergen levels expressed per gram of dust and allergen levels expressed per square metre of the sampled surface. Variance ratios were smaller when samples were taken at shorter time intervals than at longer time intervals. CONCLUSION: Over a period of 4 years, mite and cat allergens measured in house dust are sufficiently stable to use single measurements with confidence in epidemiological studies. The within-home variance was larger when samples were taken 8 years apart so that over such long periods, repetition of sampling is recommended. 相似文献
935.
936.
937.
938.
939.
Quantitative diagnostic performance of myocardial perfusion SPECT with attenuation correction in women. 总被引:1,自引:0,他引:1
Arik Wolak Piotr J Slomka Mathews B Fish Santiago Lorenzo Daniel S Berman Guido Germano 《Journal of nuclear medicine》2008,49(6):915-922
Attenuation correction (AC) for myocardial perfusion SPECT (MPS) had not been evaluated separately in women despite specific considerations in this group because of breast photon attenuation. We aimed to evaluate the performance of AC in women by using automated quantitative analysis of MPS to avoid any bias. METHODS: Consecutive female patients--134 with a low likelihood (LLk) of coronary artery disease (CAD) and 114 with coronary angiography performed within less than 3 mo of MPS--who were referred for rest-stress electrocardiography-gated 99mTc-sestamibi MPS with AC were considered. Imaging data were evaluated for contour quality control. An additional 50 LLk studies in women were used to create equivalent normal limits for studies with AC and with no correction (NC). An experienced technologist unaware of the angiography and other results performed the contour quality control. All other processing was performed in a fully automated manner. Quantitative analysis was performed with the Cedars-Sinai myocardial perfusion analysis package. All automated segmental analyses were performed with the 17-segment, 5-point American Heart Association model. Summed stress scores (SSS) of > or =3 were considered abnormal. RESULTS: CAD (> or =70% stenosis) was present in 69 of 114 patients (60%). The normalcy rates were 93% for both NC and AC studies. The SSS for patients with CAD and without CAD for NC versus AC were 10.0 +/- 9.0 (mean +/- SD) versus 10.2 +/- 8.5 and 1.6 +/- 2.3 versus 1.8 +/- 2.5, respectively; P was not significant (NS) for all comparisons of NC versus AC. The SSS for LLk patients for NC versus AC were 0.51 +/- 1.0 versus 0.6 +/- 1.1, respectively; P was NS. The specificity for both NC and AC was 73%. The sensitivities for NC and AC were 80% and 81%, respectively, and the accuracies for NC and AC were 77% and 78%, respectively; P was NS for both comparisons. CONCLUSION: There are no significant diagnostic differences between automated quantitative MPS analyses performed in studies processed with and without AC in women. 相似文献
940.