全文获取类型
收费全文 | 1564篇 |
免费 | 103篇 |
出版年
2023年 | 6篇 |
2022年 | 9篇 |
2021年 | 33篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 27篇 |
2017年 | 34篇 |
2016年 | 57篇 |
2015年 | 52篇 |
2014年 | 69篇 |
2013年 | 100篇 |
2012年 | 110篇 |
2011年 | 97篇 |
2010年 | 53篇 |
2009年 | 53篇 |
2008年 | 75篇 |
2007年 | 82篇 |
2006年 | 79篇 |
2005年 | 82篇 |
2004年 | 62篇 |
2003年 | 65篇 |
2002年 | 66篇 |
2001年 | 31篇 |
2000年 | 32篇 |
1999年 | 19篇 |
1998年 | 18篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 15篇 |
1994年 | 11篇 |
1993年 | 15篇 |
1992年 | 12篇 |
1991年 | 9篇 |
1990年 | 8篇 |
1989年 | 10篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 10篇 |
1985年 | 6篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1913年 | 8篇 |
1912年 | 5篇 |
1908年 | 6篇 |
1907年 | 4篇 |
1904年 | 7篇 |
1865年 | 5篇 |
排序方式: 共有1667条查询结果,搜索用时 15 毫秒
1.
Viktor Schiffner 《Plant Systematics and Evolution》1909,59(3):84-89
Ohne Zusammenfassung 相似文献
2.
3.
4.
Attempt to detect recombination between B-F and B-L genes within the chicken B complex by serological typing,in vitro MLR,and RFLP analyses 总被引:1,自引:1,他引:0
Karel Hála Anne-Marie Chaussé Yves Bourlet Olli Lassila Viktor Hasler Charles Auffray 《Immunogenetics》1988,28(6):433-438
In search for recombinants within the chicken major histocompatibility B complex, 1155 animals from crosses between the congenic lines CB (B12) and CC (B4) were tested with alloantibodies and monoclonal antibodies for the B-F (class I), B-L (class II), and B-G (class IV) antigens and by mixed lymphocyte reaction. The absence of detectable recombination was confirmed by restriction fragment length polymorphism analysis with B-L
and B-F probes. Together with previous reports, this indicates that the distance between the B-F and B-L loci is below 0.01 centimorgan. 相似文献
5.
Miroslav Flieger Jaroslav Votruba Vladimír Křen Sylvie Pažoutová Viktor Rylko Přemysl Sajdl Zdeněk Reháček 《Applied microbiology and biotechnology》1988,29(2-3):181-185
Summary Kinetic parameters of production of clavine alkaloids were evaluated in twoClaviceps purpurea strains. Mutagenesis brought about enhanced resistance of the biosynthetic system towards alkaloids. Addition of glucose into the fermentation medium altered the zero order kinetics of production to activation-inhibition kinetics. The glucose treatment allowed performance of both elymoclavine-inhibitionless and clavine alkaloid-decompositionless fermentations if a combination of fermentation and separation units in a closed loop was used.Nomenlacture
k
1
rate constant of agroclavine synthesis (mg Agro · mg Elymo/l·g DW·day for stage 1, mg Agro/g DW·day for stage 2)
-
k
2
parameter describing inhibition of agroclavine formation rate by elymoclavine (mg Elymo/l)
-
k
3
specific rate of agroclavine decay (l/g DW·day)
-
k
4
maximal specific rate of elymoclavine synthesis (stage 1, 1/g DW·day, stage 2, mg Elymo/g DW·day)
-
k
4
–
maximal specific rate of elymoclavine synthesis in stage 1 (inhibition-activation mechanism) (mg Elymo/g DW·day)
-
k
5
physiological constant describing the elymoclavine decay rate (l2/g DW·day·mg Elymo)
-
k
5
–
physiological constant describing the activation of elymoclavine biosynthesis by elymoclavine (mg Elymo/l)
-
k
6
physiological constant describing the repression of elymoclavine biosynthesis by elymoclavine (mg Elymo/l)
-
k
7
maximal specific growth rate (1/day)
-
k
8
specific rate of biomass decay (l/g DW·day)
-
A
agroclavine concentration (mg/l)
-
E
elymoclavine concentration (mg/l)
-
r
A
specific rate of agroclavine biosynthesis (mg Agro/g DW·day)
-
r
E
specific rate of elymoclavine biosynthesis (mg Elymo/g DW·day)
-
r
i
specific rate of alkaloid biosynthesis (mg alkaloid/g DW·day)
-
X
dry biomass concentration (g/l)
-
specific growth rate (1/day)
Abbreviations Agro
agroclavine
- Elymo
elymoclavine
- Chano
chanoclavine
- DW
dry weight of biomass 相似文献
6.
Correlation of Stomatal Conductance with Photosynthetic Capacity of Cotton Only in a CO2-Enriched Atmosphere: Mediation by Abscisic Acid? 下载免费PDF全文
Some evidence indicates that photosynthetic rate (A) and stomatal conductance (g) of leaves are correlated across diverse environments. The correlation between A and g has led to the postulation of a “messenger” from the mesophyll that directs stomatal behavior. Because A is a function of intercellular CO2 concentration (ci), which is in turn a function of g, such a correlation may be partially mediated by ci if g is to some degree an independent variable. Among individual sunlit leaves in a cotton (Gossypium hirsutum L.) canopy in the field, A was significantly correlated with g (r2 = 0.41, n = 63). The relative photosynthetic capacity of each leaf was calculated as a measure of mesophyll properties independent of ci. This approach revealed that, in the absence of ci effects, mesophyll photosynthetic capacity was unrelated to g (r2 = 0.06). When plants were grown in an atmosphere enriched to about 650 microliters per liter of CO2, however, photosynthetic capacity remained strongly correlated with g even though the procedure discounted any effect of variable ci. This “residual” correlation implies the existence of a messenger in CO2-enriched plants. Enriched CO2 also greatly increased stomatal response to abscisic acid (ABA) injected into intact leaves. The data provide no evidence for a messenger to coordinate g with A at ambient levels of CO2. In a CO2-enriched atmosphere, though, ABA may function as such a messenger because the sensitivity of the system to ABA is enhanced. 相似文献
7.
Viktor Reinhardt 《Zoo biology》1992,11(1):61-66
The sequence in which 14 laboratory rhesus macaques left their home enclosure during a routine catching procedure was recorded on 30 occasions during 6 weeks. The animals were trained to voluntarily exit one by one and enter a transport cage for weighing and/or treatment. Mean weekly exit orders cross-correlated significantly, and individuals retained their exit positions with remarkable consistency throughout the study period. An animal's position did not depend on its sex, age, or dominance rank. The oldest female never failed to enter the transport cage as number 1. When she was prevented from taking the lead, the group was hesitant but eventually proceeded in the usual order. Food was a strong, yet not absolute, incentive for the monkeys to cooperate. If they could not expect a reward, they took more time before proceeding, but did so in the habitual order. The predictability of the exit sequence has practical managerial value because it makes it possible for a single person to quickly catch a selected group member when necessary. 相似文献
8.
Olle Johansson Marita Hilliges Claes-Göran Östenson Elvi Sandberg Suad Efendic Viktor Mutt 《Cell and tissue research》1991,263(2):395-398
Summary The occurrence of diazepam-binding inhibitor (DBI), isolated and characterized from porcine upper intestine, was examined in the pancreas of Sprague-Dawley albino rats using indirect immunofluorescence. The polypeptide was found in the endocrine Langerhans islets and, utilizing double-labelling controls, it was shown to be present within the peripherally located glucagon-containing cells. Regulation of islet hormone production may therefore be under DBI control. 相似文献
9.
10.
Myhre L. G.; Hartung G. H.; Nunneley S. A.; Tucker D. M. 《Journal of applied physiology》1985,59(2):559-563
Circulatory fluid shifts were studied in middle-aged runners (6 males and 5 females, ages 32-58 yr) during a 42.2-km marathon race run in mild weather (dry-bulb temperature = 17.5-20.4 degrees C). Running times for the subjects were 3:12-4:40 (mean values were 3:34 for males and 4:10 for females). Venous blood samples were taken without stasis in all subjects seated at rest before the start of the race and within 3 min of finishing; eight of the subjects also paused for samples at 6 and 27 km during the race. At 6 km, body weight loss averaged less than 1%, whereas plasma volume (PV) had decreased by 6.5% in male subjects and 8.6% in female subjects. By the end of the race, hypohydration had reached 3.2% in male subjects and 2.9% in female subjects, but PV in both groups remained stable. Sweat rates during the race averaged 545 and 429 g X m-2 X h-1 for male and female subjects, respectively, with ad lib. water intake replacing 21-72% of fluid loss. Increases in plasma protein concentration throughout the race reflected the observed initial decrease in PV. The interpretation of PV responses to exercise and/or hypohydration is critically dependent on selection of base-line conditions; we were able to control for posture-exercise effects by treating the early exercise (6 km) sample as the base line for examining the effects of later fluid loss. Under these conditions, the vascular compartment resisted volume depletion. The ability to maintain stable PV can be explained in part by relationships among oncotic and hydrostatic pressures in the intra- and extravascular fluid compartments. 相似文献