全文获取类型
收费全文 | 4694篇 |
免费 | 288篇 |
国内免费 | 13篇 |
出版年
2024年 | 7篇 |
2023年 | 71篇 |
2022年 | 175篇 |
2021年 | 252篇 |
2020年 | 184篇 |
2019年 | 283篇 |
2018年 | 220篇 |
2017年 | 160篇 |
2016年 | 213篇 |
2015年 | 235篇 |
2014年 | 273篇 |
2013年 | 393篇 |
2012年 | 333篇 |
2011年 | 351篇 |
2010年 | 191篇 |
2009年 | 180篇 |
2008年 | 177篇 |
2007年 | 167篇 |
2006年 | 150篇 |
2005年 | 129篇 |
2004年 | 122篇 |
2003年 | 105篇 |
2002年 | 106篇 |
2001年 | 49篇 |
2000年 | 31篇 |
1999年 | 39篇 |
1998年 | 26篇 |
1997年 | 24篇 |
1996年 | 14篇 |
1995年 | 12篇 |
1994年 | 24篇 |
1993年 | 13篇 |
1992年 | 18篇 |
1991年 | 17篇 |
1990年 | 13篇 |
1989年 | 14篇 |
1988年 | 26篇 |
1987年 | 13篇 |
1986年 | 18篇 |
1985年 | 18篇 |
1984年 | 9篇 |
1983年 | 14篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 13篇 |
1977年 | 12篇 |
1976年 | 10篇 |
1973年 | 10篇 |
1971年 | 7篇 |
排序方式: 共有4995条查询结果,搜索用时 15 毫秒
191.
Comparison of Th1 and Th2 responses in non-healing and healing patients with cutaneous leishmaniasis
Maryam Shahi Masoud Mohajery Seyyed Ali Akbar Shamsian Hossein Nahrevanian Seyyed Mohammad Javad Yazdanpanah 《Reports of Biochemistry & Molecular Biology》2013,1(2):43-48
Background:
Cutaneous leishmaniasis is an endemic disease in many regions of Iran, including the city of Mashhad. In recent years, some cases have not responded to Glucantime, the usual treatment for this disease. The cellular immune response caused by T-helper type 1 (Th1) cells has an important role in protection against leishmaniasis, and activation of the T-helper type 2 (Th2) response causes progression of the disease. By analyzing these responses we hope to find a more effective treatment than that currently in use for leishmaniasis patients.Methods:
The cellular immune responses in 60 cases of non-healing and healing cutaneous leishmaniasis, and individuals in a control group, were analyzed by measuring cytokines released by peripheral blood mononuclear cells (PBMCs) when stimulated with Leishmania major antigens by Enzyme Linked Immuno Sorbent Assay (ELISA).Results:
Subjects from the healing group secreted more interleukin-12 (IL-12) and interferon gamma (IFN-γ) (p<0.05) and less interleukins -4, -5, -10 (IL-4, IL-5, and IL-10) (p<0.005) and -18 (IL-18) (p=0.003) than the non-healing group.Conclusions:
The results demonstrate that secretion of cytokines that activate Th2 response including IL-4, IL-5 and IL-10 in non-healing subjects was higher than healing subjects and secretion of cytokines that activate Th1 response including IL-12 and IFN-γ in healing subjects was higher relative to the non-healing subjects. In this study it has been shown that the level of IL-18 progresses disease in non-healing patients when the level of IL-12 gets decreased. Key Words: Cytokines, Cutaneous leishmaniasis, Glucantime 相似文献192.
Sherif E. Hussein Osama A. Hassan Malcolm H. Granat 《Biomedical signal processing and control》2013,8(6):534-541
Alternative or complementary medicine emphasizes therapies that are claimed to improve quality of life, prevent disease, and address conditions that conventional medicine has limited success in curing. There are many techniques which are prevalent in many countries and these can cause harm if not scientifically evaluated. The objective of this paper is to validate the use of iridology to diagnose kidney abnormalities. Two subject groups were evaluated: one was 168 subjects free from kidney disease and the other was 172 subjects with chronic renal failure. The procedure to acquire, process and classify the iris images was designed in such a way that avoids any dependency on the iridologists by using wavelet analysis and Adaptive Neuro-Fuzzy Inference System. The results show a correct classification for both subjects with kidney problems and normal subjects of 82% and 93%, respectively. The proposed technique conducted on a systemic disease with ocular manifestations showed encouraging results. However, it is necessary to perform extensive studies with diseases that do not have ocular manifestations according to conventional medicine in order to validate iridology as a valid scientific technique. 相似文献
193.
Soheir M. El Nahas Mona A. Bibars Dalia A. Taha Hassan I. El-Sayyad 《Journal of Genetic Engineering and Biotechnology》2013,11(1):75-77
The present study investigates CSN1S1 casein gene polymorphism in Egyptian buffalo. CSN1S1 was analyzed in 17 unrelated Egyptian lactating buffalo. The amplified segment includes the last 43 amino acids of Exon 17 and part of Intron 17. In the present study we report for the first time the presence of 2 variants 178Ser (TCA) and 178Leu (TTA) in Egyptian buffalo CSN1S1 gene. The genotypic frequencies in the investigated Egyptian buffalo sample were 0.47, 0.058 and 0.47 for homozygous 178Ser, for homozygous 178Leu and heterozygous 178Leu/Ser, respectively. The 178Ser and 178Leu variant frequencies are 0.64 and 0.36, respectively which indicates the superiority of variant 178Ser in Egyptian buffalo. The allelic frequency in Egyptian buffalo is not much different from the corresponding allelic frequency in Italian buffalo (0.69 and 0.31 for 178Ser and 178Leu, respectively) as reported by Chianese et al. [3]. This is not surprising since they both belong to Mediterranean type. 相似文献
194.
195.
Hassan Mahomed Rodney Ehrlich Tony Hawkridge Mark Hatherill Lawrence Geiter Fazlin Kafaar Deborah Ann Abrahams Humphrey Mulenga Michele Tameris Hennie Geldenhuys Willem Albert Hanekom Suzanne Verver Gregory Dudley Hussey 《PloS one》2013,8(3)
Background
Tuberculosis (TB) is a major public health problem globally. Little is known about TB incidence in adolescents who are a proposed target group for new TB vaccines. We conducted a study to determine the TB incidence rates and risk factors for TB disease in a cohort of school-going adolescents in a high TB burden area in South Africa.Methods
We recruited adolescents aged 12 to 18 years from high schools in Worcester, South Africa. Demographic and clinical information was collected, a tuberculin skin test (TST) performed and blood drawn for a QuantiFERON TB Gold assay at baseline. Screening for TB cases occurred at follow up visits and by surveillance of registers at public sector TB clinics over a period of up to 3.8 years after enrolment.Results
A total of 6,363 adolescents were enrolled (58% of the school population targeted). During follow up, 67 cases of bacteriologically confirmed TB were detected giving an overall incidence rate of 0.45 per 100 person years (95% confidence interval 0.29–0.72). Black or mixed race, maternal education of primary school or less or unknown, a positive baseline QuantiFERON assay and a positive baseline TST were significant predictors of TB disease on adjusted analysis.Conclusion
The adolescent TB incidence found in a high burden setting will help TB vaccine developers plan clinical trials in this population. Latent TB infection and low socio-economic status were predictors of TB disease. 相似文献196.
Maryam?Pourabdollah Mohammad?Bahmanyar Eshetu?G.?Atenafu Donna?Reece Jian?Hou Hong?ChangEmail author 《Journal of hematology & oncology》2016,9(1):123
The aim of this study is to assess nucleoprotein expression of IKZF1/3 in patients with relapsed/refractory multiple myeloma (MM) who received lenalidomide-based therapy and correlated them with their clinical outcomes. A total of 50 patients diagnosed with MM were entered in the study with the median follow-up of 86.4 months. By immunohistochemistry (IHC), IKZF1 and IKZF3 were expressed in 72 and 58% of the cases, respectively. IKZF1 and IKZF3 expressions were associated with longer median progression free survival (P?=?0.0029 and P?<?0.0001) and overall survival (P?=?0.0014 and P?<?0.0001). IKZF3 expression also appears predicted a favorable response to the lenalidomide-based therapy. 相似文献
197.
Background: Fragmentation can fundamentally alter the structure of tropical forests. However, the impacts of fragmentation may vary significantly among regions and lead to different outcomes.Aims: We examined the structure, composition and dynamics of a forest fragment in Singapore to investigate reasons for the apparent resilience of this forest to long-term isolation.Methods: We conducted 5 censuses of 12,688 trees ≥1-cm dbh in a 2-ha plot on the edge of the fragment between 1993 and 2012.Results: Stem density and basal area were not significantly different between 1993 and 2012 and were typical of other south-east Asian forests. However, there were short-term decreases in both variables after droughts in 1997 and 2009, both followed by recovery. Total mortality rate over the 19 years was 3.3% year?1, considerably higher than other tropical forests in Asia, but it was balanced by high recruitment. The 10 most abundant species were primary forest species, pioneer species comprised <5% of all stems, and none of the 338 species in the plot was exotic. However, species abundances changed more than expected by chance for 86 species, and the rank order of the commonest species changed significantly. Species abundance changes were not related to known species traits.Conclusions: Despite the long period of isolation, we found a surprising level of resilience of the Bukit Timah forest. While the forest may be more sensitive to the effects of climatic fluctuations at decadal time scales, there were very few signs of forest degradation in this diverse fragment of tropical forest. 相似文献
198.
199.
Matthew J. O’Brien Ji Young Lee Mercedes R. Carnethon Ronald T. Ackermann Maria C. Vargas Andrew Hamilton Nivedita Mohanty Sarah S. Rittner Jessica N. Park Amro Hassan David R. Buchanan Lei Liu Joseph Feinglass 《PLoS medicine》2016,13(7)
BackgroundIn 2015, the United States Preventive Services Task Force (USPSTF) recommended targeted screening for prediabetes and diabetes (dysglycemia) in adults who are aged 40 to 70 y old and overweight or obese. Given increasing prevalence of dysglycemia at younger ages and lower body weight, particularly among racial/ethnic minorities, we sought to determine whether the current screening criteria may fail to identify some high-risk population subgroups.ConclusionsTargeted diabetes screening based on new USPSTF criteria may detect approximately half of adult community health center patients with undiagnosed dysglycemia and proportionately fewer racial/ethnic minorities than whites. Future research is needed to estimate the performance of these screening criteria in population-based samples. 相似文献
200.