全文获取类型
收费全文 | 1029篇 |
免费 | 97篇 |
出版年
2022年 | 13篇 |
2021年 | 37篇 |
2020年 | 21篇 |
2019年 | 38篇 |
2018年 | 34篇 |
2017年 | 32篇 |
2016年 | 40篇 |
2015年 | 49篇 |
2014年 | 43篇 |
2013年 | 65篇 |
2012年 | 55篇 |
2011年 | 73篇 |
2010年 | 41篇 |
2009年 | 33篇 |
2008年 | 60篇 |
2007年 | 50篇 |
2006年 | 40篇 |
2005年 | 37篇 |
2004年 | 41篇 |
2003年 | 24篇 |
2002年 | 18篇 |
2001年 | 26篇 |
2000年 | 21篇 |
1999年 | 21篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 11篇 |
1994年 | 4篇 |
1993年 | 13篇 |
1992年 | 11篇 |
1991年 | 24篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 7篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1978年 | 5篇 |
1976年 | 4篇 |
1973年 | 4篇 |
1972年 | 6篇 |
1971年 | 3篇 |
1966年 | 3篇 |
排序方式: 共有1126条查询结果,搜索用时 359 毫秒
101.
Anand Kumar Seema Singh Satyajit Pradhan Ram C Shukla Mumtaz A Ansari Tej B Singh Rohit Shyam Saroj Gupta 《World journal of surgical oncology》2007,5(1):1-6
Background
Von Hippel-Lindau (VHL) disease is an autosomal dominant inherited disease. It is relatively recent that type 2C was identified as a separate group solely presenting with pheochromocytomas. As an illustration, an interesting case is presented of a pregnant woman with refractory hypertension. It proved to be the first manifestation of bilateral pheochromocytomas. The family history may indicate the diagnosis, but only identification of a germ line mutation in the DNA of a patient will confirm carriership.Case presentation
A 27 year pregnant patient with intra uterine growth retardation presented with hypertension and pre-eclampsia. Magnetic resonance imaging revealed bilateral adrenal pheochromocytoma. She underwent laparoscopic adrenelectomy and a missense mutation (Gly93Ser) in exon 1 of the VHL gene on chromosome 3 (p25 - p26) was shown in the patient, her father and her daughter confirming the diagnosis of VHL.Conclusion
In almost all VHL families molecular genetic analysis of DNA will demonstrate an inherited mutation. Because of the involvement in several organs, periodic clinical evaluation should take place in a well coordinated, multidisciplinary setting. VHL disease can be classified into several subtypes. VHL type 2C patients present with pheochromocytomas without evidence of haemangioblastomas in the central nervous system and/or retina and a low risk of renal cell carcinoma. Therefore, in such families, periodic clinical screening can be focussed on pheochromocytomas. 相似文献102.
Samadi Mitra Beigi Laleh Yadegari Fatemeh Ansari Alireza Madjid Majidzadeh-A Keivan Eskordi Maryam Farahmand Leila 《Genetica》2022,150(5):289-297
Genetica - Although predicting the effects of variants near intron-exon boundaries is relatively straightforward, predicting the functional Exon Splicing Enhancers (ESEs) and the possible effects... 相似文献
103.
The ability of the freshwater alga, Chlorella kessleri, to maintain a carbon concentrating mechanism when grown at acid pH was investigated. The alga grows over the pH range 4.0–9.0 and was found to take up bicarbonate and CO2 actively when grown at pH 6.0. However, when grown at acid pH (below 5.5), it does not have active CO2 uptake. The acidotolerant species maintained an internal pH of 6.1–7.5 over the external pH range 4.5–7.5, thus the pH difference between the cell interior and the external medium was large enough to allow for the diffusive uptake of CO2 at acid external pH. Mass spectrometric monitoring of O2 and CO2 fluxes by suspensions of C. kessleri, grown at acid pH, and maintained at pH 7.5 showed that the rates of O2 evolution did not exceed those of CO2 uptake. The final CO2 compensation concentrations of 14.0–17.7 µM reached by photosynthetic cells were above the CO2 equilibrium concentration in the external medium, indicating a lack of active CO2 uptake at acid pH. Chlorella kessleri accumulated CO2 with internal concentrations that were 9.9, 18.7 and 22.7‐fold that of the external medium for cells grown, respectively, at pH 4.5, 5.0 and 5.5. The ability of C. kessleri cells to accumulate high intracellular concentrations of inorganic carbon at acid pH would provide a sufficiently high concentration of CO2 at the active site of Rubisco thus allowing the alga to maintain growth rates similar to those at alkaline pH. 相似文献
104.
Uday Veer Singh Amar Abhishek Monika Bhaskar Neeraj Tandan Nasreen Ghazi Ansari Netra Pal Singh 《Bioinformation》2015,11(3):138-144
In this study, distribution of metal accumulation and their biological changes of Indian mustard plants (Brassica nigra L.) grown in
soil irrigated with different concentration of rayon grade paper effluent (RGPE, 25%, 50%, 75%, 100%, v/v) were studied. A
pronounced effect was recorded at 50% (v/v) RGPE on germination of seeds, amylase activity and other growth parameters in
Indian mustard plants. An increase in the chlorophyll and protein contents was also recorded at <50% (v/v) RGPE followed by a
decrease at higher concentrations of RGPE (>75%). A significant increase lipid peroxidation was recorded, which was evidenced by
the increased malondialdehyde (MDA) content in shoot, leaves and seeds in tested plant at all the concentrations of RGPE. This
Indian mustard plants (Brassica nigra L.) are well adapted for tolerance of significant amount of heavy metals due to increased level
of antioxidants (cysteine and ascorbic acid) in root shoot and leaves of treated plants at all concentration of RGPE. Moreover, it is
also important that RGPE should be treated to bring down the metal concentration well within the prescribed limit prior to use in
agricultural soil for ferti-irrigation. 相似文献
105.
A new species of freshwater crab, Potamonautes
isimangaliso
sp. n., is described from the western shores of False Bay, Hluhluwe, within the iSimangaliso Wetland Park, South Africa. While bearing a superficial resemblance to Potamonautes
lividus, the new species has been found to be genetically distinct, diverging from the former by 7.4–7.8% in mtDNA. Potamonautes
isimangaliso most closely resembles Potamonautes
lividus, but is distinguished by a unique suite of carapace characters, colouration, and size. The new species also lives in close association with oxygen-poor, fresh ephemeral pans, while the habitat of Potamonautes
lividus is well above the surface water line of the closest water body. An updated identification key for the Potamonautes species of South Africa is provided. 相似文献
106.
Ali MA Ismail R Choon TS Pandian S Hassan Ansari MZ 《Journal of enzyme inhibition and medicinal chemistry》2011,26(4):598-602
In this study, a series of novel 3-(substituted phenyl)-6,7-dimethoxy-3a,4-dihydro-3H-indeno[1,2-c]isoxazole analogues were synthesized and evaluated for antimycobacterial activity against Mycobacterium tuberculosis (MTB) H(37)Rv and isoniazid resistant M. tuberculosis (INHR-MTB). All the newly synthesized compounds were showing moderate to high inhibitory activities. The compound 6,7-dimethoxy-3-(4-chloro phenyl)-4H-indeno[1,2-c]isoxazole (4b) was found to be the most promising compound, active against MTB H(37)Rv and INHR-MTB with minimum inhibitory concentrations of 0.22 and 0.34 μM. 相似文献
107.
Jitendra Nath Tiwari Prashant Chaturvedi Nasreen Gazi Ansari Devendra Kumar Patel Sudhir Kumar Jain Ramesh Chandra Murthy 《Soil & Sediment Contamination》2011,20(3):315-328
Petroleum products are one of the major sources of energy for industry and daily life. Growth of the petroleum industry and shipping of petroleum products has resulted in the pollution. Populations living in the vicinity of oil refinery waste sites may be at greater risk of potential exposure to polycyclic aromatic hydrocarbons (PAH) through inhalation, ingestion, and direct contact with contaminated media. PAH have often been found to coexist with environmental pollutants including heavy metals due to similar pollution sources. The levels and distribution patterns of Σ16 PAH (sum of the 16 PAH) and heavy metals (lead, copper, nickel, cobalt, and chromium) were determined in soil and sediment in the vicinity (5 km radius) of an oil refinery in India. Concentrations of Σ16 PAH in the soils and sediments were found to be 60.36 and 241.23 ppm, respectively. Higher amount of PAH in sediments as compared to soil is due to low water solubility of PAH, settled in the bottom of aquatic bodies. The levels of lead, copper, nickel, cobalt, and chromium (total) in soil were 12.52, 13.52, 18.78, 4.84, and 8.29 ppm, while the concentrations of these metals in sediments were 16.38, 47.88, 50.15, 7.07, and 13.25 ppm, respectively. Molecular diagnostics indices of PAH (Ratio of Phenanthrene/Anthracene, Fluranthene/Pyrene) calculated for soil and sediment samples indicate that the oil refinery environment is contaminated with PAH from petrogenic as well as pyrolytic origin and heavy vehicular traffic on the Agra- Delhi National highway. Sixteen PAH priority pollutants were detected in the United States in entire samples collected near oil refinery areas and concentrations of Σ16 PAH in soil was found to be 1.20 times higher than the threshold value for PAH in soil by ICRCL (Inter-Departmental Committee on the Redevelopment of Contaminated Land). This concentration could lead to disastrous consequences for the biotic and abiotic components of the ecosystem and may affect the soil quality, thus impairing plant growth and its bioaccumulation in food chain. 相似文献
108.
109.
Hassan Azari Sharareh Sharififar Maryam Rahman Saeed Ansari Brent A. Reynolds 《Journal of visualized experiments : JoVE》2011,(47)
In mammalians, stem cells acts as a source of undifferentiated cells to maintain cell genesis and renewal in different tissues and organs during the life span of the animal. They can potentially replace cells that are lost in the aging process or in the process of injury and disease. The existence of neural stem cells (NSCs) was first described by Reynolds and Weiss (1992) in the adult mammalian central nervous system (CNS) using a novel serum‐free culture system, the neurosphere assay (NSA). Using this assay, it is also feasible to isolate and expand NSCs from different regions of the embryonic CNS. These in vitro expanded NSCs are multipotent and can give rise to the three major cell types of the CNS. While the NSA seems relatively simple to perform, attention to the procedures demonstrated here is required in order to achieve reliable and consistent results. This video practically demonstrates NSA to generate and expand NSCs from embryonic day 14-mouse brain tissue and provides technical details so one can achieve reproducible neurosphere cultures. The procedure includes harvesting E14 mouse embryos, brain microdissection to harvest the ganglionic eminences, dissociation of the harvested tissue in NSC medium to gain a single cell suspension, and finally plating cells in NSA culture. After 5-7 days in culture, the resulting primary neurospheres are passaged to further expand the number of the NSCs for future experiments.Download video file.(69M, mov) 相似文献
110.